Synthesis of carbamates from carbon dioxide promoted by organostannanes and alkoxysilanes

A cooperative methoxy transfer between orthosilicate esters and organotin oxides was developed for the synthesis of various N-alkyl and N-aryl carbamates from carbon dioxide in up to 97% isolated yield. The reaction is highly selective and N-alkylated amines are not observed. Density functional theory calculations of the reaction were performed and, together with NMR observations, a plausible mechanism featuring the catalytic regeneration of dialkyltin dialkoxide is proposed.