Catalytic Oxidative Carbonylation of Arylamines to Ureas with W(CO)6/I2 as Catalyst

The oxidative carbonylation of aniline to N,N'-diphenylurea was carried out by using W(CO)(6) as the catalyst, I-2 as the oxidant, CO as the carbonyl source and 4-(dimethylamino)pyridine (DMAP) as base. The reaction conditions were optimized with respect to different bases, molar ratio of DMAP/iodine, temperature, time, and CO pressure. Various p-substituted arylamines can be converted into the respective symmetrical and unsymmetrical N,N'-disubstituted ureas in moderate to good yields. The reaction demonstrated broad tolerance of functionality.