Stereospecific Construction of Chiral Quaternary Carbon Compounds from Chiral Secondary Alcohol Derivatives
作者:Yukio Masaki、Hideki Arasaki、Masashi Iwata
DOI:10.1246/cl.2003.4
日期:2003.1
Chiral tertiary dichloromethylcarbinol derivatives, prepared by stereospecific α C–H insertion reaction of dichlorocarbene with protected chiral secondary alcohols, were converted into intermediary α-chloroepoxides which gave stereospecifically chiral quaternary carbon compounds, α-aminoacids via α-azide-aldehydes and α-cyanoacetic acids through cyanation, respectively. The fashion generating the quaternary
Chiral tertiary dichloromethylcarbinol derivatives 2, prepared from protected chiral secondary alcohols 1, were converted stereospecifically into chiral quaternary α-oxygenated aldehyde derivatives 4 and 11 via intermediary α-chloroepoxides 3 under weakly basic conditions (K 2 CO 3 /ΜeOH/r.t.). The fashion generating the quaternary centers was proved to be quite different depending on the substrates:
由受保护的手性仲醇1制备的手性叔二氯甲基甲醇衍生物2在弱碱性条件(K 2 CO 3 /MeOH/rt)下经由中间α-氯环氧化物3立体定向地转化为手性季α-氧化醛衍生物4和11。证明生成四元中心的方式因底物而异:非苄基底物 2a 的构型反转和苄基底物 2b 的表观保留。