Selectivity in Lewis acid-mediated fragmentations of peroxides and ozonides: application to the synthesis of alkenes, homoallyl ethers, and 1,2-dioxolanes †
ylides derived from short-chain trialkylphosphines in the Wittig-type olefinationreactions toward the synthesis of alkenes, including stilbenes, styrenes, and 1,3-dienes, as well as reagents for homologation reactions, are described. The methods allow easy access to alkenes with high (E)-stereoselectivity in good yield. These reactions are conducted with weak bases in aqueous media, which allows easy
Migratory Hydrogenation of Terminal Alkynes by Base/Cobalt Relay Catalysis
作者:Xufang Liu、Bingxue Liu、Qiang Liu
DOI:10.1002/anie.201916014
日期:2020.4.20
an analogous protocol for alkyne substrates is yet to be developed. Herein, a base and cobalt relay catalytic process for the selective synthesis of (Z)-2-alkenes and conjugated E alkenes by migratory hydrogenation of terminalalkynes is disclosed. Mechanistic studies support a relay catalytic process involving a sequential base-catalyzed isomerization of terminalalkynes and cobalt-catalyzed hydrogenation
Diazirines in carbenoid reactions catalyzed by rhodium(II) carboxylates
作者:Michael P. Doyle、Kenneth G. High、Su-Min Oon、Antonio K. Osborn
DOI:10.1016/s0040-4039(00)99399-7
日期:1989.1
Diazo compounds formed by thermal or photolytic rearrangement of 3-alkyl-3-phenyl-diazirines in the presence of catalytic amounts of rhodium(II) perfluorobutyrate are effectively directed to metal carbenoid products with minimal competition from processes which are dominant when the diazo compound is used directly or when the diazirine is decomposed in the absence of the catalyst.
A tandem Aldol-Grob reaction of ketones with aromatic aldehydes
作者:George W. Kabalka、David Tejedor、Nan-Sheng Li、Rama R. Malladi、Sarah Trotman
DOI:10.1016/s0040-4020(98)00976-4
日期:1998.12
Aromatic aldehydes react with ketones to produce(E)-1-aryl-1-alkenes via a tandem Aldol-Grob cleavage reaction sequence. The reaction, initiated by boron trifluoride, also produces a carboxylic acid fragment.
A simple and efficient <i>in situ</i> generated copper nanocatalyst for stereoselective semihydrogenation of alkynes
作者:Byoung Yong Park、Taeho Lim、Min Su Han
DOI:10.1039/d1cc02685b
日期:——
aryl–alkyl, and aliphatic alkynes were selectively reduced to (Z)-alkenes affording up to 99% isolated yield. The semihydrogenation of terminal alkynes to alkenes and gram-scale applications were also reported. In addition to eliminating catalystpreparation, the proposed approach is simple and practical and serves as a suitable alternative method to the conventional Lindlar catalyst.
开发一种简单、有效且实用的 ( Z ) 炔烃选择性半氢化方法被认为是有机实验室规模易于获得的应用所必需的。在本文中,炔烃的( Z )-选择性半氢化反应是使用铜纳米催化剂实现的,该催化剂通过将氨硼烷添加到硫酸铜的乙醇溶液中而原位生成。不同类型的炔烃,包括芳基-芳基、芳基-烷基和脂肪族炔烃被选择性地还原为 ( Z)-烯烃的分离产率高达 99%。还报道了末端炔烃半氢化成烯烃和克级应用。除了不需要催化剂制备外,所提出的方法简单实用,可作为传统 Lindlar 催化剂的合适替代方法。