Bis(trimethylsilyl)ketene acetals as 1,3-dinucleophiles. Formation of an anhydride from (pentacarbonyl)(phenylethoxy)tungstacarbene

The carbene complex (CO)5Wdouble bond; length as m-dashC(Ph)OEt (1) reacts with the ketene acetal Me2Cdouble bond; length as m-dashC(OSiMe3)2 (2) in the presence of t-BuOK to give the anhydride C12H12O3 (3) characterized by an X-ray analysis, upon cleavage of both oxygen–silicon bonds, elimination of the ethoxy group, insertion of CO, and elimination of W(CO)4.