Synthesis of Isocyanates, Carbamates and Ureas

Isocyanates are readily affordable by oxidative carbonylation of the corresponding amines using palladium/copper (or iron) catalysts for example using stoichiometric amounts of Pd(II) [85]. 

These isocyanates are in fact very rarely isolated, since they react immediately with the starting amine to yield the corresponding symmetrical ureas carbamates are obtained when alcoholic solvents are used (Table 

Interesting results have recently been obtained using tellurium catalysts [90] due to the intrinsic instability of tellurium-dihydride a direct dehydrogenative carbonylation is feasible  

---