Rapid access to bicyclic δ-lactones via carbene-catalyzed activation and cascade reaction of unsaturated carboxylic esters

Abstract

Carboxylic esters are an excellent choice of substrates in organic synthesis. Here we demonstrate that carbene-catalyzed activation of α,β-unsaturated ester can be developed to synthesize sophisticated multi-cyclic molecules in a single step cascade process. The iridoid-type lactone products are obtained with high stereo-selectivities, and can readily undergo further transformations.