1-substituted Vinyl Research Articles

Copper-mediated annulation of 2-(1-arylvinyl) anilines and aryl nitrosos towards 2,3-diaryl-2H-indazoles

A copper-mediated annulation of 2-(1-substituted vinyl)anilines and aryl nitrosos is developed, giving 2,3-diaryl pyrazoles in moderate to good yields.

Ligand-Controlled Regioselectivity in the Hydrothiolation of Alkynes by Rhodium N-Heterocyclic Carbene Catalysts

Rh-N-heterocyclic carbene compounds [Rh(μ-Cl)(IPr)(η(2)-olefin)](2) and RhCl(IPr)(py)(η(2)-olefin) (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-carbene, py = pyridine, olefin = cyclooctene or ethylene) are highly active catalysts for alkyne hydrothiolation under mild conditions. A regioselectivity switch from linear to 1-substituted vinyl sulfides was observed when mononuclear RhCl(IPr)(py)(η(2)-olefin) catalysts were used instead of dinuclear precursors. A complex interplay between electronic and steric effects exerted by IPr, pyridine, and hydride ligands accounts for the observed regioselectivity. Both IPr and pyridine ligands stabilize formation of square-pyramidal thiolate-hydride active species in which the encumbered and powerful electron-donor IPr ligand directs coordination of pyridine trans to it, consequently blocking access of the incoming alkyne in this position. Simultaneously, the higher trans director hydride ligand paves the way to a cis thiolate-alkyne disposition, favoring formation of 2,2-disubstituted metal-alkenyl species and subsequently the Markovnikov vinyl sulfides via alkenyl-hydride reductive elimination. DFT calculations support a plausible reaction pathway where migratory insertion of the alkyne into the rhodium-thiolate bond is the rate-determining step.

ChemInform Abstract: N-Vinyl-, N-Allyl-, N-Propenyl- and N-Propargyl-benzotriazoles: Reactions of Their Lithium Derivatives.

1-Vinylbenzotriazole undergoes lithiation at the α-carbon and subsequent reactions with electrophiles to afford 1-(1-substituted vinyl)benzotriazoles (3a–d). Similarly, 1-(1-substituted propenyl)- (9a–c, 9e, 10a–c, 10e) and 2-(1-methylpropenyl)-benzotriazoles (14 and 15) were prepared by lithiation of the corresponding 1- and 2-propenyl-benzotriazoles followed by alkylation. 1- and 2-Allylbenzotriazoles 4 and 5 are also lithiated at the α-carbon and the intermediates react with electrophiles at this position. The structures of the propenyl derivatives were supported by an alternative synthetic route via rearrangements of the corresponding allyl isomers. 1-Propargylbenzotriazole (16) undergoes lithiation first at the acetylenic CH and then at the CH2 group. The dilithiated species, produced by treatment of 16 with two equivalents of butyllithium, reacts with an electrophile first at the carbon atom adjacent to the nitrogen atom, and then at the terminal carbon atom. Hence lithiation of 16 and subsequent reactions with electrophiles afford alkylated products 17a–d, 18a–d, 19a–b and 20a–c depending upon the amount of butyllithium and of the electrophile(s) used. The structures of each class of product were supported by spectral and analytical data.

The Unprecedented Reaction of Dimethylsulfonium Methylide with Michael Acceptors: Synthesis of 1‐Substituted Vinyl Silanes and Styrenes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

The unprecedented reaction of dimethylsulfonium methylide with Michael acceptors: synthesis of 1-substituted vinyl silanes and styrenes

Rather than the usual cyclopropanation, conditions for an unprecedented elimination reaction from the adduct of dimethylsulfonium methylide and various Michael acceptors have been established leading to functionalized 1-substituted alkenes. In silyl substituted substrates (2a and 2h), where a facile Peterson-type olefination is possible from the adduct; elimination took place instead to give functionalized 1-substituted vinyl silanes. Aryl substituted Michael acceptors (2b-e, 2g and 2i-k) also underwent a similar kind of olefination to give 1-substituted styrene derivatives with moderate yields along with a side product, which arose by nucleophilic demethylation from the adduct of dimethylsulfonium methylide and arylidene malonates. Hammett studies revealed that selectivity for olefination vs. demethylation increases as the aryl substituent becomes more electron deficient. Alkylidene malonates (2f and 2l) with a beta-alkyl substituent did not favour the olefination process. Sequential addition of Michael acceptors and alkyl halides to a mixture of dimethylsulfonium methylide and sodium dimsylate provided olefination followed by alkylation on the active methine group. A mechanistic pathway has been formulated from the studies of a few sulfonium methylides.

A Convenient Synthetic Method for Preparing 2,5-Disubstituted 1,6-Methano[10]annulenes from 1,6-Diacetylcyclohepta-1,3,5-triene

Abstract The reaction of 1,6-diacetylcyclohepta-1,3,5-triene with various Grignard reagents gave high yields of addition products 5, which were treated with a catalytic amount of p-toluenesulfonic acid or pyridinium p-toluenesulfonate to afford 2,5-disubstituted 2,3-dihydro-1,6-methano[10]annulenes 6 via 1,6-bis(1-substituted vinyl)cyclohepta-1,3,5-trienes 8 and 2,5-disubstituted 3,4-dihydro-1,6-methano[10]annulenes 9. On the other hand, reactions under more forcing conditions gave the rearrangement products: 4,7-disubstituted 1,2-benzocyclohepta-1,3-dienes 7. The oxidation of 6 with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone gave the 2,5-disubstituted 1,6-methano[10]annulens 4 in moderate-to-good yields. Conversion from 5 into 4 can be achieved by a one-flask procedure, providing a convenient synthetic method for preparing the title annulenes, particularly 2,5-diaryl ones. The reaction mechanism from 8 to 6, 7, and 9 is discussed on the basis of semiempirical molecular orbital calculations.

Theoretical Study of the Reaction of Dimethyl Acetylenedicarboxylate with 1-Methyl-2-(1-substituted vinyl)pyrroles

A theoretical study of the transition structure for the electrophilic attack step of the 1-methyl-2-vinylpyrrole to dimethyl acetylenedicarboxylate is reported with analytical gradients at AM1 and PM3 semi-empirical levels and ab initio at 3-21G level. The geometry, electronic structure, and vector components are qualitatively computer level and model independent The competition of the Michael addition reactions and Diels-Alder reactions of 1-methyl-2-(1-substituted vinyl)pyrroles with dimethyl acetylenedicarboxylate has been studied at the PM3 semi-empirical level.

INDO [intermediate neglect of differential overlap] theoretical studies. Geometry of 1-substituted vinyl radicals and 1-fluorovinyl cations

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTINDO [intermediate neglect of differential overlap] theoretical studies. Geometry of 1-substituted vinyl radicals and 1-fluorovinyl cationsCharles U. Pittman Jr., Lowell D. Kispert, and Thurman B. Patterson Jr.Cite this: J. Phys. Chem. 1973, 77, 4, 494–501Publication Date (Print):February 1, 1973Publication History Published online1 May 2002Published inissue 1 February 1973https://doi.org/10.1021/j100623a015RIGHTS & PERMISSIONSArticle Views35Altmetric-Citations8LEARN 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 (965 KB) Get e-Alerts

Substituted vinyl ethers Communication 1. Synthesis of ethyl 1-substituted vinyl ethers

1. With the object of synthesizing 1-substituted vinyl ethers, the conditions for the elimination of HBr from 2-bromoalkyl ethers [1-(bromomethyl)alkyl ethers] were determined more precisely. 2. α-(Bromomethyl)benzyl ethyl ether, ethyl 1-propyl vinyl ether, and ethyl 1-isopentylvinyl ether were prepared for the first time.

Preparations and Reactivities of 1-Substituted Vinyl Isocyanotes.

Preparations and Reactivities of 1-Substituted Vinyl Isocyanotes.