Synthesis of enantiopure 12-azido and 12-amino alcohols via regio- and stereoselective ring–opening of enantiopure epoxides by sodium azide in hot water

摘要

A practical and convenient method for the efficient and regio- and stereoselective ring-opening of enantiopure monosubstituted epoxides by sodium azide under hydrolytic conditions is reported. The ring–opening of enantiopure styryl and pyridyl (S)-epoxides by N3⁻ in hot water takes place preferentially at the internal position with complete inversion of configuration to produce (R)-2-azido ethanols with up to 99% enantio- and regioselectivity, while the (S)-adamantyl oxirane provides mainly the (S)-1-adamantyl-2-azido ethanol in excellent yield. In general, 1,2-amino ethanols were obtained in high yield and excellent enantiopurity by the reduction of the chiral 1,2-azido ethanols with PPh3 in water/THF, and then converted into the Boc or acetamide derivatives.