Stereoselective Formation of α-Alkylidene Cyclic Carbonates via Carboxylative Cyclization of Propargyl Alcohols in Supercritical Carbon Dioxide

Carboxylative cyclization of propargyl alcohols in supercritical carbon dioxide (scCO2) containing P(n-C4H9)3 as a catalyst proceeded smoothly to give α-alkylidene-1,3-dioxolan-2-ones. Internal propargyl alcohols afforded Z-alkyl-idene cyclic carbonates exclusively. CO2 incorporation was markedly promoted under supercritical conditions, possibly due to the facile formation of a putative P(n-C4H9)3−CO2 adduct as a key intermediate.