Oxidative Carbonylation of Primary Amines to Ureas Using Tungsten Carbonyl Catalysts1

The iodo-bridged tungsten(IV) dimer [(CO) 2 W(NPh)I 2 ] 2 ( 1 ) has been demonstrated to be a catalyst for the oxidative carbonylation of primary amines to 1,3-disubstituted ureas. The amine complexes (CO) 2 I 2 W(NPh)(NH 2 R) [R = n -Bu ( 2a ), R = n -Pr ( 2b ), R = t -Bu ( 2c )] and [(CO) 2 IW(NPh)(NH 2 R) 2 ] + [R = n -Bu ( 4a ), R = n -Pr ( 4b )] have been isolated from reactions of 1 with primary amines. Complexes 2a − c and 4a − b have been shown to lie along the pathway to the catalytically active species. In addition, it has been determined that primary amines can be oxidatively carbonylated to 1,3-disubstituted ureas using W(CO) 6 as catalyst and I 2 as the oxidant.