137298-83-0Relevant academic research and scientific papers
Transformation of β-chalcogeno alkenylboranes into tetrasubstituted olefins
Gerard, Julien,Hevesi, László
, p. 367 - 381 (2007/10/03)
In view of generating trisubstituted vinylic chalcogen derivatives, β-chalcogeno alkenylboranes generated through the chalcogen electrophile induced rearrangements of 1-alkynyltrialkyl borates have been subjected to Suzuki-Miyaura coupling and to boron to copper transmetalation followed by alkylation. Some of the trisubstituted vinyl sulfides obtained by this latter strategy have been converted efficiently into the title olefins through the NiCl2(dmpe) catalyzed coupling with various Grignard reagents.
Chalcogen electrophile induced rearrangement of 1-alkynyltrialkyl borates: Controlled syntheses of trisubstituted olefins from 1-alkynes
Gerard, Julien,Hevesi, László
, p. 9109 - 9121 (2007/10/03)
The reaction of 1-alkynyltrialkyl borates with sulfenyl, selenenyl and tellurenyl halides produces β-chalcogeno alkenylboranes in good yields, with a cis relationship between the boron and the chalcogen moities. Protodeborylation of these compounds by acetic acid, or by a transmetalation-protonolysis sequence, leads to vinyl chalcogenides, which can be converted to alkenes by means of a nickel catalyzed coupling with Grignard reagents. Since the last two steps occur with retention of the stereochemistry, the overall sequence represents a highly regio- and stereoselective olefin synthesis.
Free-Radical Reactions of Benzenethiol and Diphenyl Disulphide with Alkynes. Chemical Reactivity of Intermediate 2-(Phenylthio)vinyl Radicals
Benati, Luisa,Montevecchi, Pier Carlo,Spagnolo, Piero
, p. 2103 - 2109 (2007/10/02)
Reaction of benzenethiol at 100 deg C with neat alkyl- and dialkyl-acetylenes leads to virtually quantitative formation of isomeric mixtures of (E)- and (Z)-vinyl sulphide adducts in ratios which depend largely upon both the extent and the nature of alkyl substitution.Results are explained in terms of rapidly interconverting sp2-hybridized (E)- and (Z)-1-alkyl-2-(phenylthio)vinyl radical intermediates which can undergo hydrogen transfer from benzenethiol to an extent which is essentially dependent upon the steric hindrance of their cis-2-substituent.Consistent results are provided by related radical reactions of diphenyl disulphide with alkyl-substituted alkynes to afford varying amounts of 1,2-bis(phenylthio)ethylene adducts ascribable to SH2 reaction of the resulting 1-alkyl-2-(phenylthio)vinyl radicals with the disulphide present.Under analogous conditions benzenethiol and diphenyl disulphide react with phenylacetylenes to give vinyl sulphide or bissulphide adducts in a trans-stereoselective fashio.The findings are interpreted by suggesting, for the intermediate sp-hybridized 1-phenyl-2-(phenylthio)vinyl radicals, the occurrence of significant bonding interaction between the unpaired electron and the adjacent sulphur, which would essentially prevent attack of radical scavenger on the side cis to PhS.Evidence is also presented that 1-phenyl-2-(phenylthio)vinyl radicals can exhibit homolytic intramolecular cyclization reactions, leading to benzothiophene products to a comparatively much greater extent than the 1-alkyl-2-substituted analogues; however, 1-tert-butyl-2-(phenylthio)vinyl radical would represent a special case.
