Halogen-Free Synthesis of Carbamates from CO2 and Amines Using Titanium Alkoxides.

A direct synthesis of carbamates from amines and carbon dioxide in the presence of Ti(OR)4 (R= nBu ( 1), Me ( 2), Et ( 3), nPr ( 4)) was investigated. Aniline was reacted with titanium n-butoxide ( 1) in the presence of carbon dioxide (5 MPa) to give the corresponding n-butyl N-phenylcarbamate (BPC) in nearly quantitative yield (99 %) within 20 min. Furthermore, 1 could be regenerated upon reaction with n-butanol during water removal. The recovered 1 could then be reused in a subsequent reaction. [ABSTRACT FROM AUTHOR]