Nickel(II)-catalyzed synthesis of unsymmetrical carbodiimides using molecular oxygen as an oxidant from isocyanides and primary amines
作者:Takao Kiyoi、Norihiko Seko、Kohichiro Yoshino、Yoshihiko Ito
DOI:10.1021/jo00071a021
日期:1993.9
In the course of our studies of a practical synthesis of the antihypertensive drug 1, a general and convenient preparation of N,N'-disubstituted carbodiimides 2 was achieved by the nickel(II)-catalyzed reaction of isocyanides with primary amines, using oxygen gas as an oxidant. A palladium(0)/oxygen catalytic system was also useful, giving 2 in good yield, although palladium(II) was inert. A variety of metal oxides and organic peroxides were not effective as the oxidant in the carbodiimide synthesis, with the exception of Ag2O and HgO. The present synthesis of carbodiimides was applicable to the preparation of N-(3-chloro-5-cyanophenyl)-N-tert-pentylcarbodiimide (2a), a precursor of the antihypertensive drug 1.