Enantioselective synthesis of β-pyrazole-substituted alcohols through an asymmetric ring-opening reaction of meso-epoxides

摘要

An efficient and practical synthesis of optically pure β-pyrazole- substituted alcohols was achieved by an asymmetric ring-opening reaction of meso-epoxides with pyrazole derivatives as the nucleophile. In the presence of 1 mol % of an N,N′-dioxide-Sc(OTf) _3 complex, excellent enantioselectivity and yields were obtained from meso-epoxides. The process could also be used for a mixture of cis- and trans-stilbene oxides. A proposed transition-state model is provided.