Mild and Efficient Synthesis of (<i>Z</i>)-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)-α-chloroalkylidene-β-lactones was developed. Using the readily available optically active propargylic alcohols allows convenient synthesis of the corresponding (Z)-α-chloroalkylidene-β-lactones with high ee values. cis-Chloropalladation was observed as the major pathway, which is unique as compared to the reported data.