Linear Coupling of Three CO Ligands of Chromium Hexacarbonyl Leading to Functionalized Butenolides via Fischer Carbene Complexes

Abstract

Up to three CO ligands of [Cr(CO)6] can be incorporated in a linear fashion as functional groups of butenolides via alkynyl(alkoxy)carbene complexes of chromium. The key step is the biomimetic reduction of the carbene group with N-methyl dihydropyridine [Eq. (1)], which induces the cascade insertions of the triple bond and of two CO groups.