Catalytic Synthesis of Saturated Azacycles using Transborylation

Abstract

A simple, catalytic synthesis of pyrrolidines through the intermolecular cyclisation-homologation of azido-butenes was enabled by a hydroboration, 1,2-metallate rearrangement and B-N/B-H transborylation reactoin sequence. Substitution at the C1; C2; C3-positions of the pyrrolidine ring is well tolerated. Extension of this methodology to azido-propenes and azidopentenes with the aim of accessing azetidines and pyrrolidines respectively revealed the formation of an aza-bora heterocycle and a saturated azido-pentane boronic acid pinacol ester.