Chiral Hydroperoxides as Oxygen Source in the Catalytic Stereoselective Epoxidation of Allylic Alcohols by Sandwich-Type Polyoxometalates: Control of Enantioselectivity through a Metal-Coordinated Template
作者:Waldemar Adam、Paul L. Alsters、Ronny Neumann、Chantu R. Saha-Möller、Dieter Seebach、Albert K. Beck、Rui Zhang
DOI:10.1021/jo034923z
日期:2003.10.1
The epoxidation of allylic alcohols is shown to be efficiently and selectively catalyzed by the oxidatively resistant sandwich-type polyoxometalates, POMs, namely [WZnM(2)(ZnW(9)O(34))(2)](q)(-) [M = OV(IV), Mn(II), Ru(III), Fe(III), Pd(II), Pt(II), Zn(II); q = 10-12], with organic hydroperoxides as oxygen source. Conspicuous is the fact that the nature of the transition metal M in the central ring
烯丙醇的环氧化被证明是有效和选择性地被抗氧化的三明治型多金属氧酸盐,即[WZnM(2)(ZnW(9)O(34))(2)](q)(-)催化[M = OV(IV),Mn(II),Ru(III),Fe(III),Pd(II),Pt(II),Zn(II);q = 10-12],有机氢过氧化物为氧源。显而易见的是,多金属氧酸盐中心环中过渡金属M的性质会显着影响烯丙基醇环氧化反应的反应性,化学选择性,区域选择性和立体选择性。首次证明了氧钒(IV)取代的POM,即[ZnW(VO)(2)(ZnW(9)O(34))(2)](12-)是高度化学选择性的,区域选择性和立体选择性催化剂,用于烯丙基醇的清洁环氧化。高对映选择性(er值高达95:5)已使用[ZnW(VO)(2)(ZnW(9)O(34))(2)](12)(-)和具有空间需求的TADOOL衍生的氢过氧化物TADOOH作为再生手性氧源实现。因此,POM催化的具有出色催化效率(高达42