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

Under solvent-free conditions the reaction of epoxides 1a-i with trimethylsilylazide (2) catalyzed by polystiryl-supported fluoride (PS-DABCOF(2)) 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.