Access to 1,3-oxazine-2,4-diones/1,3-thiazine-2,4-diones via organocatalytic CO2/COS incorporation into allenamides

Organocatalyzed [4 + 2] annulation of CO2/COS with allenamides is firstly reported to synthesize 1,3-oxazine-2,4-diones and 1,3-thiazine-2,4-diones in moderate to excellent yields under mild reaction conditions. The catalytic potential of a series of Lewis base CO2 and COS adducts are particularly noted for this process, which features high regio- and chemo-selectivity, step-economy, facile scalability, and easy product derivatization. This study offers the potential for the application of organocatalytic systems for CO2 and COS chemical transformation.