A waste-minimized protocol for the preparation of 1,2-azido alcohols and 1,2-amino alcohols

Abstract

Under solvent-free conditions the reaction of epoxides 1a–i with trimethylsilylazide (2) catalyzed by polystiryl-supported fluoride (PS-DABCOF₂) has led to the efficient preparation of the corresponding O-TMS protected 1,2-azido alcohols 3a–i that, by treatment with Dowex-H, gave the related 1,2-azido alcohols 4a–i in excellent yields (83–99% and 82–96%, respectively). The use of a flow procedure has allowed us to significantly minimize waste in the preparation of representative 1,2-azido alcohols 4a, 4c and 4i that have been obtained with E-factors of 1.6, 2.1, and 1.9, respectively. The 1,2-amino alcohols 5a, 5c and 5f have been also prepared, in quantitative yields, by reduction of the corresponding O-TMS protected 1,2-azido alcohols 3a, 3c, and 3f by Pd on the Al₂O₃/HCOOH system.