Palladium-Catalyzed Cyclocarbonylation of o-Iodophenols and 2-Hydroxy-3-iodopyridine with Heterocumulenes: Regioselective Synthesis of Benzo[e]-1,3-oxazin-4-one and Pyrido[3,2-e]-1,3-oxazin-4-one Derivatives
Benzo[e]-1,3-oxazin-2-imine-4-ones (3) were synthesized by cyclocarbonylation of o-iodophenols with carbodiimides in the presence of a catalytic amount of a palladium catalyst and 1,4-bis-(diphenylphosphino)butane under CO pressure. Product yields are dep