IRON(III)CHLORIDE OXIDATION OF TRICARBONYL(VINYLKETENE)IRON(0)-ALKYNEADDUCTS

Oxidation of the adducts formed from tricarbonyl (vinylketene) iron(o) complexes and alkynes by iron(lll) chloride in methanol/water leads t o the replacement of the tricarbonyliron(o) unit with an oxygen atom d erived from the water. This pathway to furan-3(2H)-ones requires the p resence of an electron-withdrawing substituent on carbon-2 of the viny lketene-alkyne adduct. Data used to assign the structures of some of t he vinylketene-alkyne adducts used in this study included an X-ray cry stal structure analysis of the unusual lactone complex 5c.