The aldol reaction of aldehydes with bromofluoroketene ethyl trimethylsilyl acetal in the presence of a catalytic amount of a chiral Lewis acid at -78 degrees C provides a mixture of the corresponding syn- and anli-alpha-bromo-alpha-fluoro-beta-hydroxy esters with high enantioselectivities (up to 99% ee). Reaction temperature has a great influence on the stereoselectivity. The aldol reaction at -20 degrees C proceeds with high enantio- and diasteteoselectivities to preferentially afford the anti-aldols having opposite signs of optical rotation to those at -78 degrees C. (C) 1999 Elsevier Science Ltd. All rights reserved.
(NHC)AgCl catalyzed bromofluorocyclopropanation of alkenes with CFBr2CO2Na
作者:Anastasia A. Andrianova、Yulia D. Maslova、Maxim A. Novikov、Sergei E. Semenov、Oleg M. Nefedov
DOI:10.1016/j.jfluchem.2018.02.001
日期:2018.5
(monoalkyl substituted), electron-poor (haloalkenes, allylic esters, α,β-unsaturated esters) and acid/base sensitive silyl- and boronyl substituted alkenes with CFBr2CO2Na and catalytic (IPr)AgCl or (SIPr)AgCl was developed.
有效的富氟(芳基取代),电子中性(单烷基取代),贫电子(卤代烯烃,烯丙基酯,α,β-不饱和酯)和酸/碱敏感的甲硅烷基和硼烷基取代的烯烃溴氟环丙烷化的有效方法开发了CFBr 2 CO 2 Na和催化(IPr)AgCl或(SIPr)AgCl。
Haloaldehyde polymeres XIII. Polydibromofluoroacetaldehyde