使用氧代铵盐作为催化剂,已开发出未活化的烯烃向烯酮的第一个催化氧化烯丙基转移。该反应将各种三和反双取代的烯烃转化成其相应的烯酮,并在环境温度下以双键的换位以良好的收率。使用较少受阻的氮杂金刚烷型氧铵盐作为催化剂,并使用两种不同的化学计量氧化剂(即碘代苯二乙酸盐和单过氧邻苯二甲酸镁六水合物(MMPP·6 H 2 O))的组合,对于有效促进烯酮的形成至关重要。
Enantioselective Ni/N-Heterocyclic Carbene-Catalyzed Redox-Economical Coupling of Aldehydes, Alkynes, and Enones for Rapid Construction of Acyclic All-Carbon Quaternary Stereocenters
作者:Wu-Bin Zhang、Guang Chen、Shi-Liang Shi
DOI:10.1021/jacs.1c12625
日期:2022.1.12
but their enantioselective construction remains a prominent challenge. In particular, multicomponent enantioselective couplings of simple precursors to acyclic all-carbon quaternary stereocenters are very rare. We describe herein an N-heterocyclic carbene (NHC)-Ni catalyzed redox-economical three-component reaction of aldehydes, alkynes, and enones that proceeds in a highly chemo-, regio-, and enantioselective
Oxazaborolidine-catalyzed enantioselective reduction of a-methylene ketones was efficiently carried out by using borane-diethylaniline as a stoichiometric reducing agent. The combination of this method and subsequent hydrogenation of thus-formed allylic alcohol improved stereoselectivity in the reduction of 24-oxocholesteryl ester to 24-(R)-hydroxycholesteryl ester.