The Hydrogenation of Isocyanates

Abstract

During the preparation of a series of benzomorphan compounds, the Weinstock modification of the Curtius¹ re-arrangement was used to prepare the isocyanate and the corresponding amine obtained from hydrogerolysis of the benzyl carbamate. An alternate route investigated was the direct reduction of the isocyanate to the formamide. This eliminates the preparation of the carbamate and affords an ideal protecting group which can be easily removed (see reaction sequence).