Increasing rates and scope of reactions: sluggish amines in microwave-heated aminocarbonylation reactions under air.
Commercially available molybdenum hexacarbonyl serves as a convenient and solid carbon monoxide source in palladium-catalyzed aminocarbonylations of aryl bromides and iodides. This improved microwave protocol, relying on DBU as base and THF as solvent, enables rapid couplings using otherwise sluggish anilines, tert-butylamine, and free amino acids. In addition, Cr(CO)(6) and W(CO)(6) were found to be useful alternative CO-releasing reagents. Altogether, 16 different aromatic amides were synthesized under air in 35-95% yield after only 15 min of controlled microwave irradiation.
Wannberg
Johan
J
Department of Organic Pharmaceutical Chemistry, Uppsala University, Biomedical Centre, Box-574, SE-751 23 Uppsala, Sweden.
Larhed
Mats
M