Optically active α,β-unsaturated γ-lactones : Stereospecific transformation of allene carboxylic acids

Abstract Conditions of transformation of chiral allene carboxylic acids and their esters into α,β-unsaturated γ-lactones are described. It was found that in the case of 3a and 3b the lactonisation reaction was completely stereospecific. Configuration and optical purity of the title and related compounds have been established.