Carbonylative cyclization of alkynes using cobalt carbonyl species prepared via reduction of CoBr < inf > 2 < /inf > with Zn under a carbon monoxide atmosphere

Abstract

Alkyne-Co2(CO)6 complexes prepared in situ using CoBr2, Zn, and CO give the corresponding cycloentenones or cyclopentadienones on heating in toluene or in CH2Cl2 at 25°C in the presence of DMSO or amines.