Ligand-accelerated vanadium-catalysed epoxidation in water

摘要

Vanadium-catalysed epoxidarion of allylic alcohols, a classical example of ligand-decelerated catalysis, in water it turns into a ligand-accelerated process.Asymmetric epoxidation of allylic alcohols is regarded as one of the major tools for introducing chirality into organic molecules.Its wide recognition springs from the discovery by Sharpless and Katsuki of a very efficient process mediated by Ti-tartrate complexes.2 Another useful methodology,pioneered by Sharpless/ is based on V-hydroxamate complexes.Attractive features of V catalysis.4 in contrast to Ti.include low catalyst loading(1 mol% or less)and high tolerance of air and moisture.