Chemistry › Organic Chemistry

Organic Chemistry Cycloaddition Reactions

Works Count: 57529

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This cluster of papers focuses on understanding the reactivity of organic molecules, particularly in the context of cycloaddition reactions and asymmetric epoxidation. It explores concepts such as electrophilicity, nucleophilicity, and density functional theory to quantitatively characterize and comprehend the mechanisms of these reactions.

Keywords

Reactivity; Organic Chemistry; Cycloaddition Reactions; Electrophilicity; Nucleophilicity; Density Functional Theory; Asymmetric Epoxidation; Molecular Electron Density Theory; Diels-Alder Reaction; Quantitative Characterization

Molecular Orbital Theory of Orientation in Aromatic, Heteroaromatic, and Other Conjugated Molecules

1954-08-01

Kenichi Fukui , Teijiro Yonezawa , Chikayoshi Nagata +1 more

As to the LCAO MO treatment of the orientation problem in chemical reactions of π-electron systems, the frontier electron concept which has been previously introduced by the authors for explaining … As to the LCAO MO treatment of the orientation problem in chemical reactions of π-electron systems, the frontier electron concept which has been previously introduced by the authors for explaining the reactivities in aromatic hydrocarbons is subjected to an extension in the sense that the frontier orbitals are specified according to the type of reaction. Thus, fundamental postulates relating to the reactivities of π-electron systems are set up, which are believed to include general principles involved in the mechanism of both substitution and addition of electrophilic, nucleophilic, or radical type. On the basis of these postulates it is possible to predict the position of attack in conjugated molecules in all the three types of substitution as well as addition in a consistent manner. There is a nearly perfect agreement between the theoretical conclusions and experimental results hitherto reported.

Synthetic Applications of 1,3‐Dipolar Cycloaddition Chemistry Toward Heterocycles and Natural Products

2002-04-05

Albert Padwa , William H. Pearson

Nitrones (Jason N. Martin and Raymond C. F. Jones). Nitronates (Scott E. Denmark and Jeromy J. Cottell). Azomethine Ylides (L. M. Harwood and R. J. Vickers). Carbonyl Ylides (Mark C. … Nitrones (Jason N. Martin and Raymond C. F. Jones). Nitronates (Scott E. Denmark and Jeromy J. Cottell). Azomethine Ylides (L. M. Harwood and R. J. Vickers). Carbonyl Ylides (Mark C. McMills and Dennis Wright). Thiocarbonyl Ylides (Grzegorz Mloston and Heinz Heimgartner). Nitrile Oxides (Volker Jager and Pedro A. Colinas). Nitrile Ylides and Nitrile Imines (John T. Sharp). Diazoalkanes (Gerhard Maas). Azides (Chin-Kang Sha and A. K. Mohanakrishnan). Mesoionic Ring Systems (Gordon W. Gribble). Effect of External Reagents (Shuji Kanemasa). Asymmetric Reactions (Kurt Vesterager Gothelf and Karl Anker Jorgensen). Index.

Cycloaddition Reactions in Organic Synthesis

1990-01-01

William Carruthers

Handbook of organic conductive molecules and polymers

1997-01-01

Hari Singh Nalwa

Vol 1: From electron acceptor molecules to photoinduced intramolecular electron transfer systems perylene based conductors tetrachalcogenafulvalenes, metal 1,2-dichalcogenolenes and their conductive salts conductive hetero-TCNQs molecular metals and superconductors based on … Vol 1: From electron acceptor molecules to photoinduced intramolecular electron transfer systems perylene based conductors tetrachalcogenafulvalenes, metal 1,2-dichalcogenolenes and their conductive salts conductive hetero-TCNQs molecular metals and superconductors based on transition metal complexes conductivity and superconductivity in doped fullerenes electrochemistry of fullerenes photophysics, charge separation and associated device applications of conjugated polymer/fullerene composites photoconductivity in fullerenes organic photoconductive materials for xenographic photoreceptors photoconductive polymers graphite intercalation compounds electrically conductive metallophthalocyanines electrically conductive Langmuir-Blogett films magnetism of stable organic radical crystals. Vol 2: Polyacetylene electrically conductive polyacetylene copolymers perconjugated organic polymer - early synthesis attempts and applications electrochemical synthesis of polyheterocycles and their applications (-conductive polymers prepared by organometallic polycondensation poly(p-phenylenes) - preparation techniques and general properties synthesis and properties of processable polythiophenes molecular conductive materials - from polythiophenes to oligothiophenes charge-state incorporation in bis-thienyl polyenes and thienylene polyenylene oligomers and polymers polypyrroles - from basic research to technological applications polythiophene and polypyrrole copolymers polyanilines electrically conductive polytoluidines silicon containing thiophene monomers, oligomers and polymers - synthesis, characterization and properties silicon and germanium containing conductive polymers polyazines - synthesis, structure, spectroscopy and conducting properties conductive metallophthalocyanine polymers conductive polymer blends and composites organometallic conductive polymers self-doped conductive polymers. Vol 3: Crystallography of conductive polymers the structure of polythiophenes photoelectron spectroscopy of conductive polymers spectroelectrochemistry and spectroscopy of conducting polymers structural investigation of soluble conjugated polymers and modification of their structure at submicron scale with a scanning force microscope magnetic properties of conducting polymers Optically Detected Magnetic Resonance (ODMR) Studies of conjugated polymer films, LEDs, and fullerenes microwave properties of conductives polymers electrochemistry of conjugated polymers electrocatalytic properties of conductive polymers due to dispersion physical and spectroscopic properties of polypyrrole films containing transition metal complexes as counteranions thin film properties of oligothiophenes electrochroism in polyanilines thermochromism and solvatochromism in polythiophenes degradation and stability of conductive polymers. Vol 4: Transport in conducting polymers electronic structure of (conjugated polymers). (Part contents)

New Dual Descriptor for Chemical Reactivity

2004-12-13

Christophe Morell , André Grand , Alejandro Toro‐Labbé

In this paper, a new dual descriptor for nucleophilicity and electrophilicity is introduced. The new index is defined in terms of the variation of hardness with respect to the external … In this paper, a new dual descriptor for nucleophilicity and electrophilicity is introduced. The new index is defined in terms of the variation of hardness with respect to the external potential, and it is written as the difference between nucleophilic and electrophilic Fukui functions, thus being able to characterize both reactive behaviors. It is shown that the new descriptor correctly predicts the site reactivity induced by different donor and acceptor groups in substituted phenyl molecules. Also, the Dunitz-Burgi attack on ketones and aldehydes has been revisited to illustrate the stereoselective capability of this new index. Finally, its predictive ability has been tested successfully on different series of conjugated and nonconjugated carbonyl compounds.

Theory of 1,3-Dipolar Cycloadditions: Distortion/Interaction and Frontier Molecular Orbital Models

2008-07-10

Daniel H. Ess , K. N. Houk

Quantum chemical calculations of activation barriers and reaction energies for 1,3-dipolar cycloadditions by the high-accuracy CBS-QB3 method reveal previously unrecognized quantitative trends in activation barriers. The distortion/interaction model of reactivity … Quantum chemical calculations of activation barriers and reaction energies for 1,3-dipolar cycloadditions by the high-accuracy CBS-QB3 method reveal previously unrecognized quantitative trends in activation barriers. The distortion/interaction model of reactivity explains why (1) there is a monotonic decrease of ∼6 kcal/mol in the activation energy along the series oxides, imine, and ylide for the diazonium, nitrilium, and azomethine betaine classes of 1,3-dipoles; (2) nitrilium and azomethine betaines with the same trio of atoms have almost identical cycloaddition barrier heights; (3) barrier heights for the cycloadditions of a given 1,3-dipole with ethylene and acetylene have the same activation energies (mean absolute deviation of 0.6 kcal/mol) in spite of very different reaction thermodynamics (ΔΔHrxn range = 14−43 kcal/mol) and frontier molecular orbital (FMO) energy gaps. The energy to distort the 1,3-dipole and dipolarophile to the transition state geometry, rather than FMO interactions or reaction thermodynamics, controls reactivity for cycloadditions of 1,3-dipoles with alkenes or alkynes. A distortion/interaction energy analysis was also carried out on the transition states for the cycloadditions of diazonium dipoles with a set of substituted alkenes (CH2CHX, X = OMe, Me, CO2Me, Cl, CN) and reveals that FMO interaction energies between the 1,3-dipole and the dipolarophile differentiate reactivity when transition state distortion energies are nearly constant.

Dioxiranes: synthesis and reactions of methyldioxiranes

1985-08-01

Robert W. Murray , Ramasubbu Jeyaraman

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDioxiranes: synthesis and reactions of methyldioxiranesRobert W. Murray and Ramasubbu JeyaramanCite this: J. Org. Chem. 1985, 50, 16, 2847–2853Publication Date (Print):August 1, 1985Publication History Published online1 May … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDioxiranes: synthesis and reactions of methyldioxiranesRobert W. Murray and Ramasubbu JeyaramanCite this: J. Org. Chem. 1985, 50, 16, 2847–2853Publication Date (Print):August 1, 1985Publication History Published online1 May 2002Published inissue 1 August 1985https://pubs.acs.org/doi/10.1021/jo00216a007https://doi.org/10.1021/jo00216a007research-articleACS PublicationsRequest reuse permissionsArticle Views8857Altmetric-Citations548LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

On finding transition states

1981-09-15

C. Cerjan , William H. Miller

An algorithm for locating transition states on a potential energy surface is described. The most important feature of the algorithm, which makes explicit use of the second derivative matrix of … An algorithm for locating transition states on a potential energy surface is described. The most important feature of the algorithm, which makes explicit use of the second derivative matrix of the potential surface, is that it is able to ’’walk uphill’’ from the minimum on a potential surface to the transition state essentially automatically. The method is illustrated by application to a two dimensional model problem, to the vinylidene–acetylene rearrangement (H2C = C:↔HC≡CH), and to the dissociation and rearrangement of formaldehyde (H2CO↔H2+CO, HCOH). The algorithm is also seen to provide an improved way of following a reaction path from a transition state down to reactants or products.

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OEstrogenic Activity of Certain Synthetic Compounds

1938-02-01

E. C. Dodds , Leon I. Goldberg , W. Lawson +1 more

Thermal electron transfer reactions in polar solvents

1974-10-01

Neil R. Kestner , Jean Logan , Joshua Jortner

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermal electron transfer reactions in polar solventsNeil R. Kestner, Jean Logan, and Joshua JortnerCite this: J. Phys. Chem. 1974, 78, 21, 2148–2166Publication Date (Print):October 1, 1974Publication History … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermal electron transfer reactions in polar solventsNeil R. Kestner, Jean Logan, and Joshua JortnerCite this: J. Phys. Chem. 1974, 78, 21, 2148–2166Publication Date (Print):October 1, 1974Publication History Published online1 May 2002Published inissue 1 October 1974https://pubs.acs.org/doi/10.1021/j100614a017https://doi.org/10.1021/j100614a017research-articleACS PublicationsRequest reuse permissionsArticle Views1416Altmetric-Citations627LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts

A further exploration of a nucleophilicity index based on the gas-phase ionization potentials

2008-07-04

Paula Jaramillo , Luís R. Domingo , Eduardo Chamorro +1 more

A new C–C bond formation model based on the quantum chemical topology of electron density

2014-01-01

Luís R. Domingo

<italic>Pseudodiradical</italic>structures and GEDT involved in the C–C single bond formation in non-polar, polar and ionic organic reactions. <italic>Pseudodiradical</italic>structures and GEDT involved in the C–C single bond formation in non-polar, polar and ionic organic reactions.

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Procedure for the catalytic asymmetric epoxidation of allylic alcohols in the presence of molecular sieves

1986-05-01

Robert M. Hanson , K. Barry Sharpless

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTProcedure for the catalytic asymmetric epoxidation of allylic alcohols in the presence of molecular sievesRobert M. Hanson and K. Barry SharplessCite this: J. Org. Chem. 1986, 51, … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTProcedure for the catalytic asymmetric epoxidation of allylic alcohols in the presence of molecular sievesRobert M. Hanson and K. Barry SharplessCite this: J. Org. Chem. 1986, 51, 10, 1922–1925Publication Date (Print):May 1, 1986Publication History Published online1 May 2002Published inissue 1 May 1986https://pubs.acs.org/doi/10.1021/jo00360a058https://doi.org/10.1021/jo00360a058research-articleACS PublicationsRequest reuse permissionsArticle Views4684Altmetric-Citations415LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Thienothiophenes, Dithienothiophenes, and Thienoacenes: Syntheses, Oligomers, Polymers, and Properties

2015-04-01

M. Emin Çınar , Turan Öztürk

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTThienothiophenes, Dithienothiophenes, and Thienoacenes: Syntheses, Oligomers, Polymers, and PropertiesMehmet Emin Cinar† and Turan Ozturk*†‡View Author Information† Department of Chemistry, Istanbul Technical University, Maslak, 34469 Istanbul, Turkey‡ Chemistry … ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTThienothiophenes, Dithienothiophenes, and Thienoacenes: Syntheses, Oligomers, Polymers, and PropertiesMehmet Emin Cinar† and Turan Ozturk*†‡View Author Information† Department of Chemistry, Istanbul Technical University, Maslak, 34469 Istanbul, Turkey‡ Chemistry Group, Organic Chemistry Laboratory, TUBITAK UME, P.O. Box 54, 41470 Gebze-Kocaeli, Turkey*Fax: +90 (212) 285 6386. E-mail: [email protected]Cite this: Chem. Rev. 2015, 115, 9, 3036–3140Publication Date (Web):April 1, 2015Publication History Received21 May 2014Published online1 April 2015Published inissue 13 May 2015https://pubs.acs.org/doi/10.1021/cr500271ahttps://doi.org/10.1021/cr500271areview-articleACS PublicationsCopyright © 2015 American Chemical SocietyRequest reuse permissionsArticle Views14886Altmetric-Citations498LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Absorption,Copolymers,Electrical conductivity,Oligomers,Polymers Get e-Alerts

Ring closure reactions of bifunctional chain molecules

1981-04-01

Gabriello Illuminati , Luigi Mandolini

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRing closure reactions of bifunctional chain moleculesGabriello Illuminati and Luigi MandoliniCite this: Acc. Chem. Res. 1981, 14, 4, 95–102Publication Date (Print):April 1, 1981Publication History Published online1 May … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRing closure reactions of bifunctional chain moleculesGabriello Illuminati and Luigi MandoliniCite this: Acc. Chem. Res. 1981, 14, 4, 95–102Publication Date (Print):April 1, 1981Publication History Published online1 May 2002Published inissue 1 April 1981https://pubs.acs.org/doi/10.1021/ar00064a001https://doi.org/10.1021/ar00064a001research-articleACS PublicationsRequest reuse permissionsArticle Views4745Altmetric-Citations843LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Chemistry of dioxiranes. 12. Dioxiranes

1989-07-01

Robert W. Murray

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChemistry of dioxiranes. 12. DioxiranesRobert W. MurrayCite this: Chem. Rev. 1989, 89, 5, 1187–1201Publication Date (Print):July 1, 1989Publication History Published online1 May 2002Published inissue 1 July 1989https://pubs.acs.org/doi/10.1021/cr00095a013https://doi.org/10.1021/cr00095a013research-articleACS … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChemistry of dioxiranes. 12. DioxiranesRobert W. MurrayCite this: Chem. Rev. 1989, 89, 5, 1187–1201Publication Date (Print):July 1, 1989Publication History Published online1 May 2002Published inissue 1 July 1989https://pubs.acs.org/doi/10.1021/cr00095a013https://doi.org/10.1021/cr00095a013research-articleACS PublicationsRequest reuse permissionsArticle Views3842Altmetric-Citations611LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Synthese von Thiophen‐ und Pyrrolderivaten

1885-01-01

C. Paal

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Highly potent and selective ligands for histamine H3-receptors

1987-05-01

J.M. Arrang , M. Garbarg , J.-C. Lancelo +5 more

Improved algorithms for reaction path following: Higher-order implicit algorithms

1991-10-15

Carlos González , H. Bernhard Schlegel

Eight new algorithms for reaction path following are presented, ranging from third order to sixth order. Like the second-order algorithm [J. Chem. Phys. 90, 2154 (1989)] these are implicit methods, … Eight new algorithms for reaction path following are presented, ranging from third order to sixth order. Like the second-order algorithm [J. Chem. Phys. 90, 2154 (1989)] these are implicit methods, i.e., they rely on the tangent (and in some cases the curvature) at the endpoint of the step. The tangent (and the curvature, if needed) are obtained by a constrained optimization using only the gradient. At most, only one Hessian calculation is needed per step along the path. The various methods are applied to the Müller–Brown surface and to a new surface whose reaction path is known analytically to test their ability to follow the reaction path and to reproduce the curvature along the path.

Tandem [4+2]/[3+2] Cycloadditions of Nitroalkenes

1996-01-01

Scott E. Denmark , Atli Thorarensen

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTandem [4+2]/[3+2] Cycloadditions of NitroalkenesScott E. Denmark and Atli ThorarensenView Author Information Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, Illinois 61801 Cite this: Chem. … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTandem [4+2]/[3+2] Cycloadditions of NitroalkenesScott E. Denmark and Atli ThorarensenView Author Information Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, Illinois 61801 Cite this: Chem. Rev. 1996, 96, 1, 137–166Publication Date (Web):February 1, 1996Publication History Received5 October 1995Revised8 November 1995Published online1 February 1996Published inissue 1 January 1996https://pubs.acs.org/doi/10.1021/cr940277fhttps://doi.org/10.1021/cr940277fresearch-articleACS PublicationsCopyright © 1996 American Chemical SocietyRequest reuse permissionsArticle Views5822Altmetric-Citations625LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Addition reactions,Cyclization,Ethers,Molecular structure,Vinyl Get e-Alerts

Recent advances in [2+2+2] cycloaddition reactions

2011-01-01

Gema Domı́nguez , Javier Pérez‐Castells

The [2+2+2] cycloaddition is an elegant, atom-efficient and group tolerant process for the synthesis of carbo- and heterocycles, mostly aromatic, involving the formation of several C–C bonds in a single … The [2+2+2] cycloaddition is an elegant, atom-efficient and group tolerant process for the synthesis of carbo- and heterocycles, mostly aromatic, involving the formation of several C–C bonds in a single step. Cyclotrimerisation is catalyzed by a variety of organometallic complexes, including more than 15 different metals. The aim of this tutorial review is to point out the most recent advances in this field and to encourage the use of this reaction enroute to complex molecules. After summarizing the most common catalysts and reaction conditions generally used, we survey the mechanistic features currently accepted for this reaction. Section 4 covers the scope of the different [2+2+2] cycloaddition versions starting with the cyclotrimerisation of three triple bonds, including nitriles, with especial emphasis on asymmetric reactions that create central, axial or planar chirality. Then, reactions that use double bonds are addressed. Finally, the most outstanding examples of natural products synthesis using [2+2+2] cycloadditions as a key step reported recently are shown.

Quantum Mechanical Predictions of the Stereoselectivities of Proline-Catalyzed Asymmetric Intermolecular Aldol Reactions

2003-02-08

Sogole Bahmanyar , K. N. Houk , Harry J. Martin +1 more

Quantum mechanical calculations were employed to predict the ratio of four stereoisomeric products expected from two complex reactions involving the aldol reactions of cyclohexanone with benzaldehyde or with isobutyraldehyde catalyzed … Quantum mechanical calculations were employed to predict the ratio of four stereoisomeric products expected from two complex reactions involving the aldol reactions of cyclohexanone with benzaldehyde or with isobutyraldehyde catalyzed by (S)-proline. Experimental tests of these predictions provide an assessment of the state-of-the-art in quantum mechanical prediction of products of complex organic reactions in solution.

Understanding the mechanism of polar Diels–Alder reactions

2009-01-01

Luís R. Domingo , J.A. Sáez

A good correlation between the activation energy and the polar character of Diels–Alder reactions measured as the charge transfer at the transition state structure has been found. This electronic parameter … A good correlation between the activation energy and the polar character of Diels–Alder reactions measured as the charge transfer at the transition state structure has been found. This electronic parameter controls the reaction rate to an even greater extent than other recognized structural features. The proposed polar mechanism, which is characterized by the electrophilic/nucleophilic interactions at the transition state structure, can be easily predicted by analyzing the electrophilicity/nucleophilicity indices defined within the conceptual density functional theory. Due to the significance of the polarity of the reaction, Diels–Alder reactions should be classified as non-polar (N), polar (P), and ionic (I).

An Efficient Catalytic Asymmetric Epoxidation Method

1997-11-01

Zhixian Wang , Yong Qiang Tu , Michael Frohn +2 more

This article describes a highly effective catalytic asymmetric epoxidation method for olefins using potassium peroxomonosulfate (Oxone, Dupont) as oxidant and a fructose-derived ketone (1) as catalyst. High enantioselectivies have been … This article describes a highly effective catalytic asymmetric epoxidation method for olefins using potassium peroxomonosulfate (Oxone, Dupont) as oxidant and a fructose-derived ketone (1) as catalyst. High enantioselectivies have been obtained for trans-disubstituted and trisubstituted olefins which can bear functional groups such as tributylsilyl ether, acetal, chloride, and ester. The enantiomeric excesses for cis-olefins and terminal olefins are not high yet. The current epoxidation shows that the catalyst efficiency is enhanced dramatically upon raising the pH. Mechanistic studies show that the epoxidation mainly proceeds via a spiro transition state, which provides a model for predicting the stereochemical outcome of the reaction. The planar transition state is likely to be the main competing pathway. The extent of the involvement of the planar mode is subject to the steric effect of the alkyl groups on the olefins.

Understanding the local reactivity in polar organic reactions through electrophilic and nucleophilic Parr functions

2012-11-14

Luís R. Domingo , Patricia Pérez , J.A. Sáez

Building upon our recent studies devoted to the bonding changes in polar reactions [RSC Advances, 2012, 2, 1334 and Org. Biomol. Chem., 2012, 10, 3841], we propose herein two new … Building upon our recent studies devoted to the bonding changes in polar reactions [RSC Advances, 2012, 2, 1334 and Org. Biomol. Chem., 2012, 10, 3841], we propose herein two new electrophilic, P+k, and nucleophilic, P−k, Parr functions based on the spin density distribution at the radical anion and at the radical cation of a neutral molecule. These local functions allow for the characterisation of the most electrophilic and nucleophilic centres of molecules, and for the establishment of the regio- and chemoselectivity in polar reactions. The proposed Parr functions are compared with both, the Parr–Yang Fukui functions [J. Am. Chem. Soc. 1984, 106, 4049] based on frontier molecular orbitals, and Yang–Mortier condensed Fukui functions [J. Am. Chem. Soc. 1986, 108, 5708] based on Mulliken charges.

Computational Design of an Enzyme Catalyst for a Stereoselective Bimolecular Diels-Alder Reaction

2010-07-15

Justin B. Siegel , Alexandre Zanghellini , Helena M. Lovick +7 more

The Diels-Alder reaction is a cornerstone in organic synthesis, forming two carbon-carbon bonds and up to four new stereogenic centers in one step. No naturally occurring enzymes have been shown … The Diels-Alder reaction is a cornerstone in organic synthesis, forming two carbon-carbon bonds and up to four new stereogenic centers in one step. No naturally occurring enzymes have been shown to catalyze bimolecular Diels-Alder reactions. We describe the de novo computational design and experimental characterization of enzymes catalyzing a bimolecular Diels-Alder reaction with high stereoselectivity and substrate specificity. X-ray crystallography confirms that the structure matches the design for the most active of the enzymes, and binding site substitutions reprogram the substrate specificity. Designed stereoselective catalysts for carbon-carbon bond-forming reactions should be broadly useful in synthetic chemistry.

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Distortion/Interaction Energy Control of 1,3-Dipolar Cycloaddition Reactivity

2007-08-09

Daniel H. Ess , K. N. Houk

Computations of activation barriers and reaction energies for 1,3-dipolar cycloadditions by a high-accuracy quantum mechanical method (CBS-QB3) now reveal previously unrecognized quantitative trends in activation barriers. The distortion/interaction theory explains … Computations of activation barriers and reaction energies for 1,3-dipolar cycloadditions by a high-accuracy quantum mechanical method (CBS-QB3) now reveal previously unrecognized quantitative trends in activation barriers. The distortion/interaction theory explains why (1) there is a monotonic decrease of ∼6 kcal/mol in the barrier height along the series oxides, imine, and ylide, for each class of 1,3-dipoles; (2) the corresponding nitrilium and azomethine betaines have almost identical cycloaddition barrier heights; (3) cycloadditions of a given 1,3-dipole with ethylene and acetylene have the same activation energies, in spite of very different reaction thermodynamics and frontier orbital gaps. There is a linear correlation between distortion energies (ΔEd⧧) and the activation barrier (ΔE⧧ = 0.75ΔEd⧧ − 2.9 kcal/mol) that is general for substituted and unsubstituted 1,3-dipoles in these cycloadditions. The energy to distort the 1,3-dipole to the geometry favorable for interaction with the dipolarophile, that is, the transition state geometry, rather than frontier molecular orbital (FMO) interactions or reaction thermodynamics, controls reactivity. Interaction energies between the 1,3-dipole and the dipolarophile differentiate dipolarophile reactivity, and FMO interactions influence this.

Catalytic asymmetric epoxidation and kinetic resolution: modified procedures including in situ derivatization

1987-09-01

Yun Gao , Janice M. Klunder , Robert M. Hanson +3 more

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCatalytic asymmetric epoxidation and kinetic resolution: modified procedures including in situ derivatizationYun Gao, Janice M. Klunder, Robert M. Hanson, Hiroko Masamune, Soo Y. Ko, and K. Barry … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCatalytic asymmetric epoxidation and kinetic resolution: modified procedures including in situ derivatizationYun Gao, Janice M. Klunder, Robert M. Hanson, Hiroko Masamune, Soo Y. Ko, and K. Barry SharplessCite this: J. Am. Chem. Soc. 1987, 109, 19, 5765–5780Publication Date (Print):September 1, 1987Publication History Published online1 May 2002Published inissue 1 September 1987https://pubs.acs.org/doi/10.1021/ja00253a032https://doi.org/10.1021/ja00253a032research-articleACS PublicationsRequest reuse permissionsArticle Views17663Altmetric-Citations1735LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

The Biological Synthesis of Cholesterol

1965-10-01

Konrad Bloch

A Molecular Orbital Theory of Reactivity in Aromatic Hydrocarbons

1952-04-01

Kenichi Fukui , Teijiro Yonezawa , Haruo Shingu

In the search for a quantitative correlation between reactivity and electronic configuration of aromatic hydrocarbons, the electron density, at each carbon atom, of the highest occupied π-orbital in the ground … In the search for a quantitative correlation between reactivity and electronic configuration of aromatic hydrocarbons, the electron density, at each carbon atom, of the highest occupied π-orbital in the ground state of the molecule is calculated by means of the LCAO method. Comparing the result of such a calculation on fifteen condensed aromatic hydrocarbons with their chemical reactivities, we find that the position at which the electron density is largest is most readily attacked by electrophilic or oxidizing reagents. It is, therefore, concluded that distinct from other π-electrons the pair of π-electrons occupying the highest orbital, which is referred to as frontier electrons, plays a decisive role in chemical activation of these hydrocarbon molecules. The theoretical significance of this discrimination of the frontier electrons in relation to the chemical activation is discussed.

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Origin of reactivity, regioselectivity, and periselectivity in 1,3-dipolar cycloadditions

1973-10-01

K. N. Houk , Joyner Sims , Charles R. Watts +1 more

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOrigin of reactivity, regioselectivity, and periselectivity in 1,3-dipolar cycloadditionsK. N. Houk, Joyner. Sims, Charles R. Watts, and L. J. LuskusCite this: J. Am. Chem. Soc. 1973, 95, … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOrigin of reactivity, regioselectivity, and periselectivity in 1,3-dipolar cycloadditionsK. N. Houk, Joyner. Sims, Charles R. Watts, and L. J. LuskusCite this: J. Am. Chem. Soc. 1973, 95, 22, 7301–7315Publication Date (Print):October 1, 1973Publication History Published online1 May 2002Published inissue 1 October 1973https://pubs.acs.org/doi/10.1021/ja00803a018https://doi.org/10.1021/ja00803a018research-articleACS PublicationsRequest reuse permissionsArticle Views3277Altmetric-Citations653LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Understanding the Reactivity of Captodative Ethylenes in Polar Cycloaddition Reactions. A Theoretical Study

2008-05-17

Luís R. Domingo , Eduardo Chamorro , Patricia Pérez

The electrophilic/nucleophilic character of a series of captodative (CD) ethylenes involved in polar cycloaddition reactions has been studied using DFT methods at the B3LYP/6-31G(d) level of theory. The transition state … The electrophilic/nucleophilic character of a series of captodative (CD) ethylenes involved in polar cycloaddition reactions has been studied using DFT methods at the B3LYP/6-31G(d) level of theory. The transition state structures for the electrophilic/nucleophilic interactions of two CD ethylenes toward a nucleophilically activated ethylene, 2-methylene-1,3-dioxolane, and an electrophilically activated ethylene, 1,1-dicyanoethyelene, have been studied, and their electronic structures have been characterized using both NBO and ELF methods. Analysis of the reactivity indexes of the CD ethylenes explains the reactivity of these species. While the electrophilicity of the molecules accounts for the reactivity toward nucleophiles, it is shown that a simple index chosen for the nucleophilicity, Nu, based on the HOMO energy is useful explaining the reactivity of these CD ethylenes toward electrophiles.

Kinetic resolution of racemic allylic alcohols by enantioselective epoxidation. A route to substances of absolute enantiomeric purity?

1981-10-01

Victor S. Martı́n , Scott S. Woodard , Tsutomu Katsuki +3 more

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetic resolution of racemic allylic alcohols by enantioselective epoxidation. A route to substances of absolute enantiomeric purity?Victor S. Martin, Scott S. Woodard, Tsutomu Katsuki, Yasuhiro Yamada, Masonari … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetic resolution of racemic allylic alcohols by enantioselective epoxidation. A route to substances of absolute enantiomeric purity?Victor S. Martin, Scott S. Woodard, Tsutomu Katsuki, Yasuhiro Yamada, Masonari Ikeda, and K. Barry SharplessCite this: J. Am. Chem. Soc. 1981, 103, 20, 6237–6240Publication Date (Print):October 1, 1981Publication History Published online1 May 2002Published inissue 1 October 1981https://pubs.acs.org/doi/10.1021/ja00410a053https://doi.org/10.1021/ja00410a053research-articleACS PublicationsRequest reuse permissionsArticle Views6801Altmetric-Citations730LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Behavior of Ylides Containing N, O, and C Atoms as Hydrogen Bond Acceptors

2000-11-01

Isabel Rozas , Ibón Alkorta , José Elguero

The hydrogen bond (HB) basicity of a series of ylides containing nitrogen, oxygen, or carbon as heavy atoms, as well as the influence of the formation of the HB complexes … The hydrogen bond (HB) basicity of a series of ylides containing nitrogen, oxygen, or carbon as heavy atoms, as well as the influence of the formation of the HB complexes on their structure, has been studied. In addition, in this paper we propose the formation of some rather strong HBs (that could be considered low-barrier hydrogen bonds, LBHBs) between ylides and different neutral molecules. The ylides chosen for the study were H3N+−N-H, Me3N+−N-H, H2O+−N-H, Me2O+−N-H, H2O+−O-, Me2O+−O-, and Me3N+−C-H2. As HB donors, classical donors such as HF, HCN, and HCCH were used. The analysis of the protonation energies of the ylides and the optimized geometries, interaction energies, and characteristics of the electron density of the complexes shows that these ylides are very good HB acceptors, forming stable complexes even with weak HB donors. With strong donors, when the proton transfer did not take place, very strong HBs were formed with quite large interaction energies and very short HB distances which could be considered as LBHBs. Moreover, we have found that the sign of the Laplacian of the electron density at the bond critical point (∇2ρBCP) and that of the energy density (HBCP) could characterize the strength of HBs. Thus, weak HBs (EI < 12.0 kcal/mol) show both ∇2ρBCP and HBCP > 0, and medium HBs (12.0 < EI < 24.0 kcal/mol) show ∇2ρBCP > 0 and HBCP < 0, while strong HBs (and therefore LBHBs; EI > 24.0 kcal/mol) show both ∇2ρBCP and HBCP < 0.

Organocatalytic Asymmetric Epoxidation of Olefins by Chiral Ketones

2004-07-13

Yian Shi

Chiral ketones have been shown to be effective organocatalysts for asymmetric epoxidation of olefins with broad substrate scope. High enantioselectivity has been obtained for a wide variety of trans and … Chiral ketones have been shown to be effective organocatalysts for asymmetric epoxidation of olefins with broad substrate scope. High enantioselectivity has been obtained for a wide variety of trans and trisubstituted olefins, as well as a number of cis olefins, with encouragingly high ee's for some terminal olefins. The stereochemical outcome of the reaction can be rationalized by a spiro transition state model.

Mechanistic Aspects of Diels‐Alder Reactions: A Critical Survey

1980-10-01

Jürgen Sauer , Reiner Sustmann

Abstract The question of concerted or consecutive bond formation arises in all types of cycloaddition reactions. Stereochemical investigations and studies of regiospecificity as well as intensive kinetic investigations with regard … Abstract The question of concerted or consecutive bond formation arises in all types of cycloaddition reactions. Stereochemical investigations and studies of regiospecificity as well as intensive kinetic investigations with regard to substituent and solvent effects, and the dependence of the reaction on temperature and pressure permit in many cases mechanistic conclusions concerning the Diels‐Alder reaction. Efforts towards a theoretical interpretation, ab initio and semiempirical calculations, the application of frontier molecular orbital theory (FMO) as well as thermochemical measurements permit a description of the energy hypersurface of these [4+2]‐cycloadditions. An attempt is made here to draw a line of distinction between the mechanistic alternatives—one‐step reaction versus two‐step reaction—considering all experimental and theoretical criteria.

Catalytic asymmetric epoxidation of unfunctionalized olefins

1990-01-01

Ryo Irie , Keiko Noda , Yoshio Ito +2 more

Using redundant internal coordinates to optimize equilibrium geometries and transition states

1996-01-15

Chunyang Peng , Philippe Y. Ayala , H. Bernhard Schlegel +1 more

A redundant internal coordinate system for optimizing molecular geometries is constructed from all bonds, all valence angles between bonded atoms, and all dihedral angles between bonded atoms. Redundancies are removed … A redundant internal coordinate system for optimizing molecular geometries is constructed from all bonds, all valence angles between bonded atoms, and all dihedral angles between bonded atoms. Redundancies are removed by using the generalized inverse of the G matrix; constraints can be added by using an appropriate projector. For minimizations, redundant internal coordinates provide substantial improvements in optimization efficiency over Cartesian and nonredundant internal coordinates, especially for flexible and polycyclic systems. Transition structure searches are also improved when redundant coordinates are used and when the initial steps are guided by the quadratic synchronous transit approach. © 1996 by John Wiley & Sons, Inc.

The Role of Frontier Orbitals in Chemical Reactions (Nobel Lecture)

1982-11-01

Kenichi Fukui

Recent Advances in the Friedländer Reaction

2009-04-10

José Marco‐Contelles , Elena Pérez‐Mayoral , Abdelouahid Samadi +2 more

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTRecent Advances in the Friedländer ReactionJosé Marco-Contelles*†, Elena Pérez-Mayoral‡, Abdelouahid Samadi†, María do Carmo Carreiras§, and Elena Soriano*†View Author Information Laboratorio de Radicales Libres y Química Computacional … ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTRecent Advances in the Friedländer ReactionJosé Marco-Contelles*†, Elena Pérez-Mayoral‡, Abdelouahid Samadi†, María do Carmo Carreiras§, and Elena Soriano*†View Author Information Laboratorio de Radicales Libres y Química Computacional (IQOG, CSIC), Madrid, Spain, Departamento de Química Inorgánica y Química Técnica, Facultad de Ciencias, Universidad Nacional de Educación a Distancia (UNED), Madrid, Spain, and iMed.UL, Research Institute for Medicines and Pharmaceutical Sciences, Faculty of Pharmacy, University of Lisbon, Av. Forcas Armadas, 1600-083 Lisbon, Portugal* To whom correspondence should be addressed. Fax: (+34) 564-48-53. E-mail: [email protected]†Laboratorio de Radicales Libres y Química Computacional.‡Universidad Nacional de Educación a Distancia (UNED).§University of Lisbon.Cite this: Chem. Rev. 2009, 109, 6, 2652–2671Publication Date (Web):April 10, 2009Publication History Received2 October 2008Published online10 April 2009Published inissue 10 June 2009https://pubs.acs.org/doi/10.1021/cr800482chttps://doi.org/10.1021/cr800482creview-articleACS PublicationsCopyright © 2009 American Chemical SocietyRequest reuse permissionsArticle Views12898Altmetric-Citations565LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Catalysts,Chemical reactions,Cyclization,Ketones,Quinolines Get e-Alerts

1,3-Dipolar cycloadditions. 76. Concerted nature of 1,3-dipolar cycloadditions and the question of diradical intermediates

1976-02-01

Rolf Huisgen

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT1,3-Dipolar cycloadditions. 76. Concerted nature of 1,3-dipolar cycloadditions and the question of diradical intermediatesRolf HuisgenCite this: J. Org. Chem. 1976, 41, 3, 403–419Publication Date (Print):February 1, 1976Publication … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT1,3-Dipolar cycloadditions. 76. Concerted nature of 1,3-dipolar cycloadditions and the question of diradical intermediatesRolf HuisgenCite this: J. Org. Chem. 1976, 41, 3, 403–419Publication Date (Print):February 1, 1976Publication History Published online1 May 2002Published inissue 1 February 1976https://pubs.acs.org/doi/10.1021/jo00865a001https://doi.org/10.1021/jo00865a001research-articleACS PublicationsRequest reuse permissionsArticle Views3338Altmetric-Citations529LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Structures of Complexes Formed by Halogen Molecules with Aromatic and with Oxygenated Solvents1

1950-01-01

Robert S. Mulliken

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructures of Complexes Formed by Halogen Molecules with Aromatic and with Oxygenated Solvents1Robert S. MullikenCite this: J. Am. Chem. Soc. 1950, 72, 1, 600–608Publication Date (Print):January 1, … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructures of Complexes Formed by Halogen Molecules with Aromatic and with Oxygenated Solvents1Robert S. MullikenCite this: J. Am. Chem. Soc. 1950, 72, 1, 600–608Publication Date (Print):January 1, 1950Publication History Published online1 May 2002Published inissue 1 January 1950https://pubs.acs.org/doi/10.1021/ja01157a151https://doi.org/10.1021/ja01157a151research-articleACS PublicationsRequest reuse permissionsArticle Views2511Altmetric-Citations806LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Handbook of Thiophene‐Based Materials

2009-07-17

Molecular Electron Density Theory: A Modern View of Reactivity in Organic Chemistry

2016-09-30

Luís R. Domingo

A new theory for the study of the reactivity in Organic Chemistry, named Molecular Electron Density Theory (MEDT), is proposed herein. MEDT is based on the idea that while the … A new theory for the study of the reactivity in Organic Chemistry, named Molecular Electron Density Theory (MEDT), is proposed herein. MEDT is based on the idea that while the electron density distribution at the ground state is responsible for physical and chemical molecular properties, as proposed by the Density Functional Theory (DFT), the capability for changes in electron density is responsible for molecular reactivity. Within MEDT, the reactivity in Organic Chemistry is studied through a rigorous quantum chemical analysis of the changes of the electron density as well as the energies associated with these changes along the reaction path in order to understand experimental outcomes. Studies performed using MEDT allow establishing a modern rationalisation and to gain insight into molecular mechanisms and reactivity in Organic Chemistry.

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Saturated bioisosteres of benzene: where to go next?

2019-01-01

Pavel K. Mykhailiuk

Saturated bioisosteres for <italic>ortho</italic>- and <italic>meta</italic>-substituted benzenes remain a current challenge for chemists. Saturated bioisosteres for <italic>ortho</italic>- and <italic>meta</italic>-substituted benzenes remain a current challenge for chemists.

Water-Promoted Organic Reactions

1994-01-01

André Lubineau , Jacques Augé , Yves Queneau

The reactions reviewed herein are those showing an unusual outcome when performed in water or in an aqueous medium. Notably, transformations are included for which the hydrophobic effect might be … The reactions reviewed herein are those showing an unusual outcome when performed in water or in an aqueous medium. Notably, transformations are included for which the hydrophobic effect might be invoked as the activation factor, as well as cases where water leads to valuable changes compared to traditional solvents, except when they are clearly due to the polarity as for example in nucleophilic substitution reactions and except when the effect comes from the addition of a few equivalents of water. 1. Introduction 2. Physicochemical Background 2.1 Structure of Water 2.2 Aqueous Solutions of Simple Molecules 2.3 Hydrophobic Effects 2.4 Reactivity in Water 3. Pericyclic Reactions 3.1 Diels-Alder Reactions 3.2 Hetero Diels-Alder Reactions 3.3 Dipolar Cycloadditions 3.4 Claisen Rearrangements 4. Nucleophilic Additions 4.1 Aldolisation (Mukaiyama Reaction) 4.2 Michael-Type Reactions 4.3 Other Nucleophilic Additions 5. Organometallic Chemistry 5.1 Barbier-Type Reactions 5.2 Transition Metal Complex Catalyzed Reactions 5.3 Other Metal-Catalyzed Reactions 6. Oxidations 7. Reductions 8. Photochemistry 9. Conclusion

The Chemistry of ketenes, allenes, and related compounds

1980-01-01

Saul Patai

A QUANTITATIVE COLOR REACTION FOR CORTISONE AND RELATED 17,21-DIHYDROXY-20-KETOSTEROIDS

1950-07-01

Curt C. Porter , Robert Silber

Strained Spirocyclobutane from Cross-[2+2]-Cycloaddition in Molecular Cages

2025-06-23

| Synfacts

Topological characterization, computational, spectroscopic (FT-IR, 1H, 13C NMR) exploration, chemical reactivity analysis of 6-(3,3-dimethyl-oxiran-2-ylidene)-5,5-dimethyl-hex-3-en-2-one

2025-06-23

R. Mohamed Hisam , P. Rajesh , E. Dhanalakshmi +3 more | Next Materials

Ultra-Long Thienoacenes

2025-06-23

| Synfacts

On the Question of the Course of the Hetero Diels–Alder Reactions Between N-(2,2,2-Trichloroethylidene)Carboxamides and Dicyclohexylcarbodiimide: A New Case of the Stepwise Zwitterionic Cycloaddition Process

2025-06-21

Przemysław Woliński , Karolina Zawadzińska-Wrochniak , Ewa Dresler +1 more | Molecules

The regioselectivity and the molecular mechanism of the Diels–Alder reactions between N-(2,2,2-trichloroethylidene)carboxamides and dicyclohexylcarbodiimide were explored based on the ωB97xd/6-311G(d) (PCM) calculations. It was found that the reaction course is … The regioselectivity and the molecular mechanism of the Diels–Alder reactions between N-(2,2,2-trichloroethylidene)carboxamides and dicyclohexylcarbodiimide were explored based on the ωB97xd/6-311G(d) (PCM) calculations. It was found that the reaction course is determined by polar local interactions. It is interesting that the most favored reaction channel is realized not via classical single-step Diels–Alder mechanism, but according to the stepwise scheme with the intervention of the zwitterionic intermediate. The details of the electron density redistribution along the reaction coordinate were explained using the ELF technique.

Addition Reactions: Cycloaddition

2025-06-13

S. R. Hussaini | Organic Reaction Mechanisms/Organic reaction mechanisms

Identifying the True Catalyst: A Mn(II) Salt versus Mn(II) Complexes in Epoxidation with m‐Chloroperbenzoic Acid

2025-06-12

Milica Savić , Aleksandra Mitrović , Božidar Čobeljić +5 more | European Journal of Organic Chemistry

The oxidant meta‐chloroperbenzoic acid (m‐CPBA) is used widely for the epoxidation of alkenes, yet its efficiency is often limited under ambient conditions. In this study we investigate the catalytic activity … The oxidant meta‐chloroperbenzoic acid (m‐CPBA) is used widely for the epoxidation of alkenes, yet its efficiency is often limited under ambient conditions. In this study we investigate the catalytic activity of a Mn(II) salt and mononuclear Mn(II) complexes, two of which are reported here for the first time, in the epoxidation of alkenes with m‐CPBA under ambient conditions. Time‐resolved Raman spectroscopy was used to monitor substrate conversion, oxidant consumption, and product formation. The data reveal that simple Mn(II) salts exhibit significantly higher catalytic activity than Mn(II) complexes, indicating that ligand coordination inhibits the reactivity of the manganese centre. The catalytic efficiency of Mn(II) perchlorate was particularly notable, achieving near‐complete oxidation of styrene within minutes under mild conditions. Furthermore, epoxidation of a range of alkenes demonstrated that Mn(II) salts provide broad substrate scope and high selectivity. These findings suggest that simple Mn(II) salts can serve as highly efficient and cost‐effective catalysts in alkene epoxidations with m‐CPBA.

Reversible conformational change coupled electron transfer (CCET) for stable redox-active molecules

2025-06-12

Christian A. Malapit , Atsushi Kitamura , Jonathan D. Evans | Research Square (Research Square)

<title>Abstract</title> Reversible electron transfer is a fundamental process that is essential in redox-active organic molecules and materials (ROMs) across biological, chemical, and energy technologies. Achieving stable and reversible redox behavior … <title>Abstract</title> Reversible electron transfer is a fundamental process that is essential in redox-active organic molecules and materials (ROMs) across biological, chemical, and energy technologies. Achieving stable and reversible redox behavior often requires careful molecular design or coupling electron transfer with a chemical step, such as proton-coupled electron transfer (PCET). In this study, we investigate a distinct stabilization mechanism based on conformational change coupled electron transfer (CCET). We show that acyclic 1,2-dicarbonyl compounds exhibit enhanced electrochemical stability by undergoing a conformational shift from skewed cis-geometries to more stable trans-conformations upon reduction, enabling stability even at more negative reduction potentials. Mechanistic studies demonstrate that CCET stabilizes the reduced state by allowing bond rotation that minimizes electron repulsion and delocalizes electron density by retaining a trans-planar geometry. Unlike PCET, which shifts reduction potentials positively, CCET enhances stability even at more negative potentials—breaking the conventional trade-off between redox potential and stability. Charge-discharge cycling of benzil shows 99.8% capacity retention over 500 cycles, demonstrating CCET as a powerful strategy for developing stable, high-performance ROMs for potential energy storage applications.

Modeling of the General Trends of Reactivity and Regioselectivity in Cyclopentadiene–Nitroalkene Diels–Alder Reactions

2025-06-04

Adrianna Fałowska , Stanisław Grzybowski , Daniel Kapuściński +2 more | Molecules

This study presents a theoretical investigation of the electronic properties of mono- and pentasubstituted cyclopentadiene analogs and variously substituted conjugated nitroalkenes bearing electron-donating and electron-withdrawing groups. Conceptual Density Functional Theory … This study presents a theoretical investigation of the electronic properties of mono- and pentasubstituted cyclopentadiene analogs and variously substituted conjugated nitroalkenes bearing electron-donating and electron-withdrawing groups. Conceptual Density Functional Theory (CDFT) and Electron Localization Function (ELF) analyses were employed to characterize the global and local reactivity indices of the reactants. The obtained data provided insights into the nucleophilic and electrophilic nature of the investigated systems, allowing for the prediction of their reactivity patterns in Diels-Alder reactions. A reactivity model for conjugated alkenes toward cyclopentadienes was developed based on correlation analysis using Hammett substituent constants. This approach enabled the prediction of reaction polarity in (4+2) cycloaddition processes, providing insight into how the electronic effects of substituents influence the reaction course. These findings contribute to a deeper understanding of structure-reactivity relationships in Diels-Alder processes.

Structural and electronic properties of novel diazahomoadamantane-based hydrazones: synthesis, characterization, and DFT insights

2025-06-03

Bshair Ali Sadeq , R. T. Alasadi , Sajid H. Guzar | Structural Chemistry

Synergistic Interplay between Intermolecular Halogen and Chalcogen Bonds in the Dihalogen Adducts of 2,5-Bis(pyridine-2-yl)tellurophene: Reactivity Insights and Structural Trends

2025-05-29

Enrico Podda , Massimiliano Arca , M. Carla Aragoni +6 more | Inorganic Chemistry

The reactivity of 2,5-bis(pyridine-2-yl)tellurophene (L) toward elemental dihalogens XY (X = Y = I, Br; X = I, Y = Cl, Br) was explored. The oxidative addition of the dihalogen … The reactivity of 2,5-bis(pyridine-2-yl)tellurophene (L) toward elemental dihalogens XY (X = Y = I, Br; X = I, Y = Cl, Br) was explored. The oxidative addition of the dihalogen molecules to the Te(II) center was observed in LI2 (1), LI2·1/2I2 (2), LBr2 (3), LBr1.63I0.37 (4), and LCl1.86I0.14 (5), which were characterized in the solid state by X-ray diffraction analysis and Raman spectroscopy. In all cases, a seesaw geometry at the chalcogen atom was observed with the linear X-Te-X moiety almost perpendicular to the tellurophene ring. The crystal packing in these compounds displays a peculiar and synergistic interplay of halogen and chalcogen bonds. A comparison with analogous compounds reported in the literature was carried out to establish the key factors determining the supramolecular arrays of noncovalent intermolecular interactions (NCIs) observed in this class of compounds.

Computational model of the formation of novel nitronorbornene analogs via Diels–Alder process

2025-05-28

Agata Karaś , Agnieszka Łapczuk-Krygier | Reaction Kinetics Mechanisms and Catalysis

Mechanistic study of the [2 + 2] cycloaddition of ethylene with ketene derivatives via MEDT

2025-05-27

Mohamed Chellegui , Ines Salhi , Ali Ben Ahmed +4 more

Exploring the bioactive potential of 3-hydroxy-3-phenyl-isoindolin-1-one: A DFT-based computational study

2025-05-26

Saiful Danish , Sheikh Alima , Sidrat +7 more

Computational investigations on the anaesthetic drug, tetracaine (TCA) by DFT, TD-DFT, molecular docking, and molecular dynamic simulation analysis

2025-05-24

Naved Azum , Khalid A. Alzahrani , Muhammad Tariq Saeed Chani +4 more

The current investigation deals with the theoretical exploration of tetracaine (TCA) employing density function theory (DFT), time-dependent density function theory (TD-DFT), molecular docking (MD), and molecular dynamic simulation (MDS). The … The current investigation deals with the theoretical exploration of tetracaine (TCA) employing density function theory (DFT), time-dependent density function theory (TD-DFT), molecular docking (MD), and molecular dynamic simulation (MDS). The B3LYP method was utilised for this study in conjunction with a 6-31++G(d,p) basis set. We computed the charge distribution of the molecule tetracaine using molecular electrostatic potential (MEP) analysis, which indicate how molecules interact and what kinds of chemical bonds they have. Additionally, population analysis and Fukui function analysis have explored charges on the atoms. This comprehensive study also includes an assessment of various parameters such as chemical hardness, chemical softness, and electrophilicity index through the Frontier Molecular Orbital (FMO) investigation. The molecule's non-linear optical (NLO) properties were conducted to ascertain the hyperpolarizability and polarity values. Lastly, molecular docking was used to look at how a ligand and two protein receptors, named monoamine oxidase A (code: 2BXR) and monoamine oxidase B (code: 1OJD), interact with a ligand. The resulting binding energies were determined to be -7.7 and -7.6 kcal/mol, respectively. Following the completion of the docking process, an investigation of conformational behaviour was conducted with the assistance of molecular dynamic simulation (MDS). These findings indicate the possible applicability of this interaction in the field of medicine. This study has the potential to be utilized in the future to advance the creation of amphiphilic drugs.

Experimental and computational investigations of two N′-(adamantan-2-ylidene)-substituted benzohydrazide derivatives: crystal structures, antiproliferative activity, molecular docking, and molecular dynamic simulations

2025-05-23

Lamya H. Al-Wahaibi , Annesha Chakraborty , Eman T. Warda +5 more

Energy-Transfer-Enabled 1,4-Amino Migration and C–O Diradical Recombination for Norrish–Yang-Type Epoxidation

2025-05-22

Danna Chen , Lulu Qin , Dan Luo +4 more

An energy-transfer-enabled photochemical strategy merges 1,4-nitrogen migration with Norrish-Yang-type epoxidation to achieve skeletal editing of molecular frameworks. This approach bypasses classical di-π-methane rearrangements, providing an oxidant-free and atom-economical route to … An energy-transfer-enabled photochemical strategy merges 1,4-nitrogen migration with Norrish-Yang-type epoxidation to achieve skeletal editing of molecular frameworks. This approach bypasses classical di-π-methane rearrangements, providing an oxidant-free and atom-economical route to epoxides via controlled C-O diradical recombination. The protocol accommodates >40 diverse substrates, including arenes, heterocycles, and bioactive motifs, enabling late-stage functionalization of complex architectures. Scalability is demonstrated through gram-scale synthesis (84% yield) and one-pot cascades. Mechanistic studies reveal a triplet energy-transfer pathway distinct from radical chain processes, with nitrogen migration directing regioselective diradical recombination.

Influence of position variation of selenium atom and electron‐withdrawing substituents on charge transport, opto‐electronic, photovoltaic, chemical reactivity indices, and thermodynamic properties of pentatetraselenophene molecules

2025-05-22

Manisha Manisha , Vijay Dangi , Brahamdutt Arya

Abstract In this research, we have studied the effect of variation in the position of the selenium atom and substitution of different electron‐withdrawing groups (─Cl, ─CN, ─COCl) in pentatetraselenophene (PTSe) … Abstract In this research, we have studied the effect of variation in the position of the selenium atom and substitution of different electron‐withdrawing groups (─Cl, ─CN, ─COCl) in pentatetraselenophene (PTSe) molecule on their charge transport, electronic, optical, photovoltaic, chemical reactivity indices, and thermodynamic properties. All the calculations of this study were performed by employing the density functional theory (DFT) and time‐dependent density functional theory (TD‐DFT) at B3LYP functional and 6–31(d,p) basis set in the gaseous state. Additionally, the density of states calculation was performed with the help of Gauss Sum software by using the DFT‐optimized structures. The results of optoelectronic properties demonstrate that the absorption wavelengths and energy gaps ( E g ) of all the investigated compounds range from 457 to 689 nm and 2.131 to 2.335 eV. In comparison, all PTSe‐based compounds had lower hole/electron reorganization energies (86–161 meV/94–202 meV) than typical materials (less than 290/276 meV), indicating that they transport electrons and holes more efficiently. Instead, all PTSe‐based compounds can be utilized as hole‐carrying materials because the hole reorganization energy is lower than the electron reorganization energies. Moreover, the difference between the hole and electron reorganization energies is less (about 3–25 meV), which means most of the examined molecules (except PSe7 ) can be employed as ambipolar charge‐transport materials. The predicted open circuit voltages of the examined compounds range from 0.975–2.179 eV, which are adequate for effective electron injection. This work highlights that the substitution of electron‐withdrawing groups and the alteration in the position of the selenium atom can be a prominent material for charge transport and ambipolar organic semiconductors. Our study serves as a supportive way for further designing and fabrication of a new type of organic semiconductor material for applications in photovoltaic solar cells, OLEDs, and OFETs.

Oxa-π,σ‑Methane Rearrangement for Epoxide Construction via Energy-Transfer Catalysis

2025-05-22

Role of Thiophene-Based Halogenated Non-Fused Ring Containing Acceptor Molecules for Efficient Organic Photovoltaics

2025-05-21

S. M. Salauddin Iqbal , Zobia Irshad , Riaz Hussain +6 more

Halogenated nonfused rings containing molecular acceptors are considered widely owing to their potential to be lightweight, and flexible, and improve the electron mobility and overall charge transfer process in organic … Halogenated nonfused rings containing molecular acceptors are considered widely owing to their potential to be lightweight, and flexible, and improve the electron mobility and overall charge transfer process in organic solar cells (OSCs). Herein, we designed a new series of nonfused ring acceptors ATH1-ATH11 by modulating the synthetic reference molecule ATH-R. Incorporating CN, [Formula: see text], [Formula: see text], F and Cl atoms greatly impacts the molecular structures and electronic properties, which could potentially enhance [Formula: see text]-[Formula: see text] stacking, electron mobility and overall charge transfer phenomenon. This designed series (ATH1-ATH11) along with the synthetic reference ATH-R is characterized by advanced quantum chemical simulations using various density functional theory (DFT) and time-dependent DFT (TD-DFT) approaches. The incorporation of those end-capped functionals helps in narrowing the energy gap of the designed series and also enhances the absorption characteristics from synthetic reference 709.62 nm to designed ATH-5 832.05 nm. The dispersion of frontier molecular orbitals reveals the formation of lower HOMO levels, when coupled with a relatively minor reduction in LUMO levels, can facilitate the narrowing of the energy gap in the materials. Moreover, the designed ATH1-ATH11 series shows reduced exciton binding energy and ex-citation energy in contrast to the synthetic reference ATH-R molecule. The reduced values of reorganization energy revealed that these molecules could be efficiently employed as efficient molecular acceptors. The charge transfer analysis of the donor: acceptor blend (PTB7-Th: ATH5) displayed a good charge transfer phenomenon at the donor–acceptor interface. Furthermore, a newly designed series (ATH1-ATH11) shows the improved optoelectronics and photovoltaic characteristics of the molecules rather than the synthetic reference ATH-R molecule. These outcomes revealed the potential of molecular modeling of halogenated nonfused rings to improve the photovoltaic performances of OSCs.

Effect of isomerism, inter-ring torsion angle and chain length in structural and electronic properties of oligothiophenes: computational study

2025-05-21

Belgacem Bezzina , Safia Himri , Mohamed Tayeb Abedghars +2 more

Trihydroxybenzaldoximes are Redox Cycling Inhibitors of ThDP-Dependent DXP Synthase

2025-05-18

Charles R. Nosal , Ananya Majumdar , Netzahualcóyotl Arroyo‐Currás +1 more

Pathogenic bacteria must swiftly adapt to dynamic infection environments in order to survive and colonize in the host. 1-Deoxy-d-xylulose-5-phosphate synthase (DXPS) is thought to play a critical role in bacterial … Pathogenic bacteria must swiftly adapt to dynamic infection environments in order to survive and colonize in the host. 1-Deoxy-d-xylulose-5-phosphate synthase (DXPS) is thought to play a critical role in bacterial adaptation during infection and is a promising drug target. DXPS utilizes a thiamine diphosphate (ThDP) cofactor to catalyze the decarboxylative condensation of pyruvate and d-glyceraldehyde-3-phosphate (d-GAP) to form DXP, a precursor to isoprenoids and B vitamins. DXPS follows a ligand-gated mechanism in which pyruvate reacts with ThDP to form a long-lived lactyl-ThDP (LThDP) adduct which is coordinated by an active-site network of residues. d-GAP binding ostensibly disrupts this network to activate LThDP for decarboxylation. Our lab previously reported trihydroxybenzaldoxime inhibitors which are competitive with respect to d-GAP, and uncompetitive with respect to pyruvate, suggesting they bind after E-LThDP complex formation. Here, we conducted mechanistic studies to determine if these compounds inhibit DXPS by preventing LThDP activation or if they act as inducers of LThDP activation. We discovered that the catechol moiety of the trihydroxybenzaldoxime scaffold undergoes oxidation under alkaline aerobic conditions, and inhibitory potency is reduced under oxygen restriction. Leveraging long-range 1H-15N HSQC NMR and electrochemical measurements, we demonstrated that the oxidized form of the trihydroxybenzaldoxime induces LThDP decarboxylation and accepts electrons from the resulting carbanion, resulting in reduction to the catechol and formation of acetyl-ThDP which hydrolyzes to form acetate. Under aerobic conditions the catechol is reoxidized. Thus, these compounds act as redox cycling, substrate-wasting inhibitors of DXP formation. These findings uncover a novel activity and mechanism of DXPS inhibition which may have implications for DXPS-mediated redox activity in bacteria. Further exploration of redox active DXPS probes may provide new insights for inhibition strategies and selective probe development.

Computational investigation of the cycloaddition reaction mechanism of 2,4,6-trimethyl-3,5-dichlorobenzonitrile N-oxide with arylacetylenes: insights from density functional theory and molecular docking

2025-05-16

Raad Nasrullah Salih , Haydar Mohammad-Salim , Muheb Algso

Étale Endomorphisms of 3-Folds. IV

2025-05-16

Yoshio Fujimoto

We classify a smooth projective 3 -fold X with \kappa(X) = -\infty of type (\mathrm{C}_{-\infty}) admitting a nonisomorphic étale endomorphism up to a finite étale covering. We classify a smooth projective 3 -fold X with \kappa(X) = -\infty of type (\mathrm{C}_{-\infty}) admitting a nonisomorphic étale endomorphism up to a finite étale covering.

The Theoretical and Experimental Study of DiazomethaneStyrene [3+2]-Cycloadditions

2025-05-15

Serhii Shuvakin , С. П. Ивонин

Pyrazolines are an important class of heterocyclic compounds known for their biological activities, making them attractive objects for medicinal chemistry. This study investigated the regioselective [3+2]-cycloaddition of diazomethane with para-substituted … Pyrazolines are an important class of heterocyclic compounds known for their biological activities, making them attractive objects for medicinal chemistry. This study investigated the regioselective [3+2]-cycloaddition of diazomethane with para-substituted styrenes featuring electron-withdrawing (EWG) and electron-donating (EDG) groups. Experimental results have demonstrated that the electronic properties of substituents significantly affect the reaction efficiency and regioselectivity, as well as the product stability. At the same time, EWG provided lower activation barriers and higher reaction yields. Calculations performed by the density functional theory (DFT) method confirmed the experimental data allowing us to understand in detail the reaction mechanism, activation energy values, and thermodynamic parameters. This integrated experimental and theoretical approach improves understanding of the effects of substituents, contributing to the rational design of substituted pyrazolines.

Catalytic Epoxidation of Rice Bran Oil via an In Situ Generated Hybrid Peracids Mechanism

2025-05-15

Mohamed Noorfazlida , Mohamad Zarqani Yeop , Intan Suhada Azmi +5 more

Mechanistic Insights into the [3+2] Cycloaddition Reaction of Azomethine Ylides with Methyl Vinyl Ketone in the Triplet Excited State: A Molecular Electron Density Theory Study

2025-05-14

Luís R. Domingo , Patricia Pérez , Assem Barakat

The [3+2] cycloaddition (32CA) reaction of an azomethine ylide with methyl vinyl ketone in the ground and first triplet excited states has been studied within the framework of Molecular Electron … The [3+2] cycloaddition (32CA) reaction of an azomethine ylide with methyl vinyl ketone in the ground and first triplet excited states has been studied within the framework of Molecular Electron Density Theory. A DFT‐based reactivity analysis indicates that, while azomethine ylide behaves as a supernucleophile in both states, vinyl ketone acts as a strong electrophile. This 32CA reaction presents a very low activation energy both in the ground state, 3.40 kcal·mol‐1, and in the triplet state, 1.47 kcal·mol‐1, in the gas phase. While in the ground state, the 32CA reaction is entirely ortho regio and fully endo stereoselective, in the triplet state it is entirely ortho regioselective but only partially endo stereoselective. In the ground state, the reaction proceeds to form the spirooxindole after passing through the transition state structure, whereas in the triplet state, the reaction stops at a biradical intermediate, which requires an intersystem crossing to yield the final spirooxindole. Analysis of the kinetic parameters of the 32CA reaction in the two states in methanol indicates that in the triplet state, the reaction is 589 times faster than in the ground state.

Synthesis and structure of 1′,4′-diphenyl-1a,1′,4′,4′′,5′′,9b-hexahydro-2′′H-dispiro[cyclopropa[l]phenanthrene-1,2′-[1,4]epoxynaphthalene-3′,3′′-thiophene]

2025-05-13

Yuewei Wen , Dasan M. Thamattoor

The title compound, C 39 H 30 OS, was inadvertently prepared as a Diels–Alder adduct between 1,3-diphenylisobenzofuran and 3-(1a,9b-dihydro-1 H -cyclopropa[ l ]phenanthren-1-ylidene)tetrahydrothiophene. A combination of fused, bridged, and spirocyclic … The title compound, C 39 H 30 OS, was inadvertently prepared as a Diels–Alder adduct between 1,3-diphenylisobenzofuran and 3-(1a,9b-dihydro-1 H -cyclopropa[ l ]phenanthren-1-ylidene)tetrahydrothiophene. A combination of fused, bridged, and spirocyclic ring systems are all featured within a single molecular structure of this highly crowded polycyclic compound.

A Comprehensive Study of the Synthesis, Spectral Characteristics, Quantum–Chemical Molecular Electron Density Theory, and In Silico Future Perspective of Novel CBr3-Functionalyzed Nitro-2-Isoxazolines Obtained via (3 + 2) Cycloaddition of (E)-3,3,3-Tribromo-1-Nitroprop-1-ene

2025-05-13

Karolina Zawadzińska-Wrochniak , Karolina Kula , Mar Ríos‐Gutiérrez +3 more

The search for new heterocyclic compounds with biological potential is one of the current challenges in modern chemistry. Therefore, the comprehensive study of (3 + 2) cycloaddition (32CA) reactions between … The search for new heterocyclic compounds with biological potential is one of the current challenges in modern chemistry. Therefore, the comprehensive study of (3 + 2) cycloaddition (32CA) reactions between a series of aryl-substituted nitrile N-oxides (NOs) and (E)-3,3,3-tribromo-1-nitroprop-1-ene (TBNP) is carried out. According to the experimental research, in all tested 32CAs, the proper (4RS,5RS)-3-aryl-4-nitro-5-tribromomethyl-2-isoxazolines are obtained as only one reaction product. In turn, the quantum-chemical MEDT study shows that the creation of heterocycles occur via the polar attack of zwitterionic moderate-nucleophilic NOs to strong electrophilic TBNP. The reactions are realized according to a two-stage, one-step asynchronous mechanism, in which the formation of the O-C(CBr3) bond takes place once the C-C(NO2) bond is already formed. What is more, the computational analysis confirmed the experimental results. At the end, the obtained 2-isoxazolines were docked to three proteins: gelatinase B, cyclooxygenase COX-1, and Caspase-7. We hope that the presented study will be helpful for searching for the future direction of application for this class of organic compounds.

First-principles structural, molecular docking, and ADMET studies on dipeptides containing N-terminal N-formylmethionine: a study in gas, implicit and explicit solvents

2025-05-12

Suresh Das , Soma Barman , G. Das

Condensed-to-bond dual descriptor for the analysis of electron density rearrangement in π-conjugated compounds

2025-05-10

Ricardo Pino‐Rios