Copper-Catalyzed Semihydrogenation of Internal Alkynes with Molecular Hydrogen
摘要:
A copper-catalyzed system using a commercially available simple N-heterocyclic carbene ligand under atmospheric pressure of H-2 (1 atm, balloon) enables the semihydrogenation of internal alkynes, which proceeds with high Z selectivity. Thus, this copper catalysis provides a useful method for the preparation of (Z)-alkenes from internal alkynes.
The reaction of lithium trialkylalkynylborate with methanesulphinyl chloride
作者:M. Naruse、K. Utimoto、H. Nozaki
DOI:10.1016/s0040-4020(01)97353-3
日期:1974.1
Treatment of lithium trialkylalkynylborates (1) with methanesulphinyl chloride gives internal acetylenes (2) in good yields. The reaction proceeds via β-methanesulphinylvinylboranes 3, followed by cis elimination of methanesulphinyl group and dialkylboron groups. The reaction mixture of B-alkyl-9-BBN and 1-lithio-1-heptyne has been treated with methanesulphinyl chloride to provide mainly a cyclooctane
Chalcogen electrophile induced rearrangement of 1-alkynyltrialkyl borates: controlled syntheses of trisubstituted olefins from 1-alkynes
作者:Julien Gerard、László Hevesi
DOI:10.1016/s0040-4020(01)00904-8
日期:2001.10
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
Transformation of β-chalcogeno alkenylboranes into tetrasubstituted olefins
作者:Julien Gerard、László Hevesi
DOI:10.1016/j.tet.2003.11.023
日期:2004.1
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
Reaction of β-hydroxy or acetoxy sulfones with Sml2 in the presence of HMPA caused effectively reductiveelimination to provide olefins. Treatment of enol phosphates, readily synthesized from β-hydroxy sulfones via keto sulfones, under the same conditions efficiently produced mono- and disubstituted acetylenes.