Vinyl Cation Equivalents Research Articles

Synthesis and Deployment of an Elusive Fluorovinyl Cation Equivalent: Access to Quaternary α-(1'-Fluoro)vinyl Amino Acids as Potential PLP Enzyme Inactivators.

Developing specific chemical functionalities to deploy in biological environments for targeted enzyme inactivation lies at the heart of mechanism-based inhibitor development but also is central to other protein-tagging methods in modern chemical biology including activity-based protein profiling and proteolysis-targeting chimeras. We describe here a previously unknown class of potential PLP enzyme inactivators; namely, a family of quaternary, α-(1'-fluoro)vinyl amino acids, bearing the side chains of the cognate amino acids. These are obtained by the capture of suitably protected amino acid enolates with β,β-difluorovinyl phenyl sulfone, a new (1'-fluoro)vinyl cation equivalent, and an electrophile that previously eluded synthesis, capture and characterization. A significant variety of biologically relevant AA side chains are tolerated including those for alanine, valine, leucine, methionine, lysine, phenylalanine, tyrosine, and tryptophan. Following addition/elimination, the resulting transoid α-(1'-fluoro)-β-(phenylsulfonyl)vinyl AA-esters undergo smooth sulfone-stannane interchange to stereoselectively give the corresponding transoid α-(1'-fluoro)-β-(tributylstannyl)vinyl AA-esters. Protodestannylation and global deprotection then yield these sterically encumbered and densely functionalized quaternary amino acids. The α-(1'-fluoro)vinyl trigger, a potential allene-generating functionality originally proposed by Abeles, is now available in a quaternary AA context for the first time. In an initial test of this new inhibitor class, α-(1'-fluoro)vinyllysine is seen to act as a time-dependent, irreversible inactivator of lysine decarboxylase from Hafnia alvei. The enantiomers of the inhibitor could be resolved, and each is seen to give time-dependent inactivation with this enzyme. Kitz-Wilson analysis reveals similar inactivation parameters for the two antipodes, L-α-(1'-fluoro)vinyllysine (Ki = 630 ± 20 μM; t1/2 = 2.8 min) and D-α-(1'-fluoro)vinyllysine (Ki = 470 ± 30 μM; t1/2 = 3.6 min). The stage is now set for exploration of the efficacy of this trigger in other PLP-enzyme active sites.

ChemInform Abstract: Copper‐Catalyzed Carboarylation of Alkynes via Vinyl Cations.

Copper-catalyzed arylation of electron rich alkynes reveals stabilized trisubstituted vinyl cation equivalents that react with pendant arene nucleophiles to form all carbon tetrasubstituted alkenes. The new process streamlines the synthesis of important medicinally relevant molecules.

Copper-Catalyzed Carboarylation of Alkynes via Vinyl Cations

Copper-catalyzed arylation of electron rich alkynes reveals stabilized trisubstituted vinyl cation equivalents that react with pendant arene nucleophiles to form all carbon tetrasubstituted alkenes. The new process streamlines the synthesis of important medicinally relevant molecules.

ChemInform Abstract: A Versatile Synthesis for 1,4-Dienes: Use of Vinyl Ethers as Vinyl Cation Equivalents.

ChemInform Abstract: A Versatile Synthesis for 1,4-Dienes: Use of Vinyl Ethers as Vinyl Cation Equivalents.

Widening the Usefulness of Epoxides and Aziridines in Synthesis

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Widening the usefulness of epoxides and aziridines in synthesis

Abstract Deprotonation of terminal epoxides and aziridines with organolithium/diamine combinations or lithium amides allows the regio- and stereoselective formation of α-lithiated species. Judicious choice of reaction conditions allows these species to operate as nucleophiles, enolate equivalents, vinyl cation equivalents, or carbenes.

ChemInform Abstract: Synthesis of Ethenyl(phenyl)iodonium Triflate (H2C=CHIPh)(OSO2CF3), and Its Application as Vinyl Cation Equivalent.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A Versatile Synthesis of 1,4‐Dienes: Use of Vinyl Ethers as Vinyl Cation Equivalents

The α,β‐dibromo ethers 2, in situ generated from the vinyl ethers 1 and bromine, react with the allylsilanes 3 in the presence of ZnCl2 to give the β‐bromo ethers 4. Treatment of 4 with Na in diethyl ether yields 1,4‐dienes 5 in 62–79% overall yield.

Synthesis of Ethenyl(phenyl)iodonium Triflate, [H2CCHIPh][OSO2CF3], and Its Application as a Parent Vinyl Cation Equivalent

Synthesis of Ethenyl(phenyl)iodonium Triflate, [H₂CCHIPh][OSO₂CF₃], and Its Application as a Parent Vinyl Cation Equivalent

ChemInform Abstract: A New Method for the α‐Vinylation of Protected α‐Amino Acids. Ethylene Oxide as Vinyl Cation Equivalent.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A New Method for the α-Vinylation of Protected α-Amino Acids; Ethylene Oxide as Vinyl Cation Equivalent

Abstract A convenient and conceptually new strategy for the transformation of α-amino acids into the corresponding α-vinyl amino acids is described; commercially available ethylene oxide serves as a vinyl cation equivalent.

Vinyl Ether–Iron Complexes as Vinyl Cation Equivalents. Preparation and Use of an α‐Acrylic Ester Cation Equivalent

AbstractThe organoiron complex 4 is readily prepared from α‐bromopyruvic ester diethyl acetal, and has been shown to serve as an effective α‐acrylic ester cation equivalent, in the synthesis of α‐methylene‐γ‐lactones. Cyclohexanone lithium enolate is transformed to either the cis or trans fused lactones 12c, t, and ethyl acetoacetate lithium enolate can be converted to the lactone 21t. The use of methyl 3‐oxohexadecanoate as starting material provides a stereospecific synthesis of protolichesterinic acid methyl ester.

Transformation of organoiron complexes of synthetic and chemical interest

Abstract

Cationic enol ether-iron complexes as vinyl cation equivalents. Synthesis of protolichesterinic ester

The reaction of lithium enolates derived from β-keto esters with complex cation 4 provides a facile route to 3,4-disubstituted α-methylene-γ-lactones.

.alpha.-Silyl aldehydes: preparation and use as stereoselective vinyl cation equivalents

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT.alpha.-Silyl aldehydes: preparation and use as stereoselective vinyl cation equivalentsPaul F. Hudrlik and Ashok K. KulkarniCite this: J. Am. Chem. Soc. 1981, 103, 20, 6251–6253Publication Date (Print):October 1, 1981Publication History Published online1 May 2002Published inissue 1 October 1981https://doi.org/10.1021/ja00410a060RIGHTS & PERMISSIONSArticle Views959Altmetric-Citations78LEARN 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 InReddit PDF (432 KB) Get e-Alerts Get e-Alerts

Enol ether-iron complexes as vinyl cation equivalents. Vinylation of enolates

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEnol ether-iron complexes as vinyl cation equivalents. Vinylation of enolatesTony C. T. Chang, Myron Rosenblum, and Sari B. SamuelsCite this: J. Am. Chem. Soc. 1980, 102, 18, 5930–5931Publication Date (Print):August 1, 1980Publication History Published online1 May 2002Published inissue 1 August 1980https://doi.org/10.1021/ja00538a049RIGHTS & PERMISSIONSArticle Views243Altmetric-Citations38LEARN 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 InReddit PDF (271 KB) Get e-Alerts Get e-Alerts

Preparation of a Trans α,β-Epoxysilane by Selective Pyrolysis

Abstract α,β-Epoxysilanes have been shown to be useful synthetic intermediates2 for the preparation of carbonyl compounds3 and stereoisomerically-pure olefins4 and heteroatom-substituted olefins5 (vinyl bromides,5 enol acetates,5 enol ethers,5 enamides,5 and vinyl mesylates6). In many of their reactions, α,β-epoxysilanes serve as stereospecific vinyl cation equivalents;4–6 therefore methods to prepare stereoisomerically-pure α,β-epoxysilanes are of considerable importance. Although other methods for preparing α,β-epoxysilanes have recently been developed,7 the only general method for preparing stereoisomerically-pure α,β-epoxysilanes is epoxidation of the corresponding vinylsilanes.