BISMUTH(III) CARBOXYLATES AS A NEW CLASS OF OXIDANTS - PYRIDINE CARBOXYLATES AND DICARBOXYLATES IN THE OXIDATIVE CLEAVAGE OF ARYL EPOXIDES AND ALPHA-KETOLS

Several Bi(III) carboxylates have been obtained through reaction of Bi 2O3 with various pyridine mono or dicarboxylic acids, and with phthali c acid. Thus, the tris-carboxylato complex Bi[qui(COO)](3) forms in th e presence of quinaldic acid (qui(COOH)), while phthalic acid yields B i[phthal(COO)(2)](OH) independently of the stoichiometry of the reacti on. A Bi(III) diphenate, PhBi(phen), was prepared from BiPh(3) and dip henic acid. These were all found to catalyze the oxidative C-C cleavag e of styrene oxide and alpha-hydroxyacetophenone to benzoic acid. This allowed us to demonstrate that the bismuth-catalyzed oxidation of sty rene oxide into benzoic acid goes through the intermediate formation o f (i) the alpha-ketol, PhCOCH(2)OH, which requires DMSO as the oxidant , and (ii) the ketoaldehyde, PHCOCHO, which results from Bi(III)-catal yzed dioxygen oxidation of the ketol.