A Straightforward Synthesis of Enantiopure Bicyclic Azetidines

Abstract

AbstractEnantiomerically pure 1‐azabicyclo[3.2.0]heptane derivatives were synthesized in a straightforward manner from readily available chiral sources, namely, enantiomerically pure epoxides and L‐proline. The key step of this synthesis relied on a diastereoselective intramolecular alkylation of a proline enolate, which led to an azetidine ring fused to a five‐membered ring. These strained bicyclic nitrogen derivatives were found to be good precursors for the preparation of azepanes, after transformation into the corresponding ammonium trifluoromethanesulfonates followed by reaction with nucleophiles.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)