Dual Lewis base–CO2 adduct/MTBD organocatalytic system was developed for the cascade reaction of CO2, propargylic alcohol, and polyhydroxy compounds to afford various functionalized cyclic carbonates in high regio- and stereoselectivity.

Lewis base-COS adducts were firstly studied as organocatalysts for the cyclization of propargylic alcohols with carbonyl sulfide.

The organocatalytic cyclization of propargylic amines/amides with carbonyl sulfide (COS) was firstly achieved by employing COS adducts of Lewis base (LB) as organocatalysts, affording various functionalized 1,3‐thiazolidine‐2‐ones, and 1,3‐thiazolidine‐2,4‐diones derivatives in a highly chemo‐ and stereoselective manner. The isotope labeling and stoichiometric experiments suggested the LB‐COS adducts preferentially mediated basic ionic pair mechanism. Furthermore, the practical application of this methodology was highlighted by the highly efficient synthesis of rosiglitazone using COS as sulfur source.