Catalytic Oxidative Carbonylation of Primary and Secondary α,ω-Diamines to Cyclic Ureas

Primary and secondary diamines can be catalytically carbonylated to cyclic ureas using W(CO) 6 as the catalyst, I 2 as the oxidant, and CO as the carbonyl source. Preparation of five-, six-, and seven-membered cyclic ureas from the diamines RNHCH 2 (CH 2 ) n CH 2 NHR ( n = 0−2; R = H, Me) and RNHCH 2 CH 2 NHR (R = Et, i -Pr, Bz) was achieved in moderate to good yields.