OXIDATION OF KETONES BY FERRIC PERCHLORATE IN THE PRESENCE OF CONJUGATED DIENES TO HEXAHYDROFURO[2,3-B]FURANS AND 1,6-DIOXASPIRO[4,4]NONANES

Iron(III) perchlorate nonahydrate (FEP) in acetonitrile in the presenc e of conjugated dienes oxidizes carbonyl compounds (aldehydes and keto nes) to alpha,alpha-diaddition products hexahydrofuro[2,3-b]-furans 3, in moderate yield (nine examples). Alpha,alpha-Disubstituted ketones afford the alpha,alpha'-diaddition products 1,6-dioxaspiro[4,4]nonanes 4 or monoaddition products 6 and 7. The isomer distribution and the i nfluence of the reaction conditions are discussed based on selective o xidative deprotonation of the carbonyl compound by iron(III) and addit ion of alpha-carbonylalkyl radicals to conjugated olefins.