A new general approach for the stereocontrolled synthesis of functionalised γ- and δ-lactams

Abstract

A new flexible approach for the stereoselective synthesis of substituted 1H-pyrrol-2(5H)-ones and 3,6-dihydro-1H-pyridin-2-ones has been developed. The general strategy employed the stereoselective reduction of a series of α,β-unsaturated ketones under chelation control to give the corresponding allylic alcohols. Overman rearrangement to install the key C–N bond followed by conversion to either prop-2-enoyl or but-3-enoyl derivatives and a ring closing metathesis reaction gave the target unsaturated γ- and δ-lactams. The synthetic utility of these compounds as building blocks was demonstrated by the preparation of the N-Boc derivative of (−)-coniine.