The rhodium-catalyzed reaction of racemic allyl alcohols with methyl phenyldiazoacetate or methyl styryldiazoacetate results in a two-step process, an initial oxonium ylide formation followed by a [2,3]-sigmatropic rearrangement. This process competes favorably with the more conventional O-H insertion chemistry as long as donor/acceptor carbenoids and highly substituted allyl alcohols are used as substrates
外消旋
烯丙醇与苯基
重氮乙酸甲酯或
苯乙烯基
重氮乙酸甲酯的
铑催化反应产生一个两步过程,首先形成氧鎓叶立德,然后进行 [2,3]-σ 重排。只要使用供体/受体类卡宾和高度取代的
烯丙醇作为底物,该过程就可以与更传统的 OH 插入
化学竞争。当反应由 Rh(2)(S-
DOSP)(4) 催化时,会以高对映选择性 (85-98% ee) 产生具有两个相邻季中心的叔 α-羟基
羧酸衍
生物。