[HCo(CO)₄]-catalyzed three-component cycloaddition of epoxides, imines, and carbon monoxide: facile construction of 1,3-oxazinan-4-ones.

The three-component [3+2+1] cycloaddition of epoxides, imines, and carbon monoxide to produce 1,3-oxazinan-4-ones has been developed by using [HCo(CO)4] as the catalyst. The reaction occurs for a wide variety of imines and epoxides, under 60 bar of CO pressure at 50 °C, to produce 1,3-oxazinan-4-ones with different substitution patterns in high yields, and provides an efficient and atom-economic route to heterocycles from simple and readily available starting materials. A plausible mechanism involves [HCo(CO)4]-induced ring-opening of the epoxide, followed by sequential addition of carbon monoxide and the imine, and then ring closure to form the product accompanied by regeneration of [HCo(CO)4].