Acid-Catalyzed Carbonylation of Lactone to Cyclic Anhydride on Tungsten Metal

Facile carbonylation of the cis-vinyl complex Cp(CO)3W[CHCH(COMe)] (2, Cp = η5-C5H5) followed by cyclization affords the γ-lactone Further carbonylation of 4 induced by the presence of acid in CH3CN gives the cyclic anhydride The reaction of 4 with Me2NH causes ring opening to yield the zwitterionic complex Cp(CO)2W[η2-Me2NC(Me)CHCHCOOH] (6). The cyclic anhydride ligand of 9 remains unchanged when 9 is treated with nucleophiles. For example, the reaction of Me2NH with 9 affords the imine-coordinated and the reaction of NaBH4 with 9 generates the (15). The structures of 4, 6, 9, and 14 have also been determined by X-ray diffraction analysis. The allylic ligand in 9 is in an endo conformation.