dialkylaminosilanes a number of newrearrangements was observed. When acted upon by ketene, dialkylaminosilanes, depending on the conditions applied, produce either amides of β-siloxyvinylacetic acid (I) (route “a”, scheme A) or amides of silylated aceticacid (II) (routes “b”, “c”). In both cases an intermediate α-siloxyvinyldialkylamine (III) was isolated which may be rearranged to give amide (II).
Trimethylsilyl‐Protected Alkynes as Selective Cross‐Coupling Partners in Titanium‐Catalyzed [2+2+1] Pyrrole Synthesis
作者:Hsin‐Chun Chiu、Ian A. Tonks
DOI:10.1002/anie.201800595
日期:2018.5.22
both identified to play key roles in this highly selective pyrrolesynthesis. This strategy provides a convenient method to synthesize multisubstituted pyrroles as well as an entry point for further pyrrole diversification through facile modification of the resulting 2‐silyl pyrrole products, as demonstrated through a short formal synthesis of the marine natural product lamellarin R.
Beyond silanol: A branched siloxane oligomer bearing terminal dialkoxysilyl groups was nonhydrolytically synthesized by direct alkoxysilylation of a tetraalkoxysilane with a chlorodialkoxysilane in the presence of the Lewis acid BiCl3 (see scheme). The reaction proceeds without the formation of intermediate silanol groups, and provides a selective route for siloxane‐based oligomers.
Enantioselective Trifluoromethylalkynylation of Alkenes via Copper-Catalyzed Radical Relay
作者:Liang Fu、Song Zhou、Xiaolong Wan、Pinhong Chen、Guosheng Liu
DOI:10.1021/jacs.8b07436
日期:2018.9.5
A novel enantioselective copper-catalyzed trifluoromethylalkynylation of styrenes, proceeding through a radical relay process, is described herein, which affords structurally diverse CF3-containing propargylic compounds in good yield with excellent enantioselectivities under very mild conditions. In addition, the reaction features wide substrate scope and good functional group tolerance. Moreover,
Alcohol‐free: A versatile, efficient, and practical synthesis of alkoxysilanes without generation of HCl involves the reaction of chlorosilanes with unsymmetrical ethers in the presence of a Lewis acid (see scheme). The reaction proceeds through selective cleavage of CO bonds and is superior to conventional processes. Industrially feasible reagents are used and only one by‐product results.