Mild and efficient synthesis of (Z)-α-chloroalkylidene-β-lactones via the PdCl2-catalyzed cyclocarbonylation of 2-alkynols

A mild and efficient methodology involving PdCl2-catalyzed cyclocarbonylation of 2-alkynols with CuCl2 for the synthesis of (Z)-alpha-chloroalkylidene-beta-lactones was developed. Using the readily available optically active propargylic alcohols allows convenient synthesis of the corresponding (Z)-alpha-chloroalkylidene-beta-lactones with high ee values. cis-Chloropalladation was observed as the major pathway, which is unique as compared to the reported data.