Enamine oxidations .2. Selective oxidative cleavage of beta,beta-disubstituted enamines using alumina supported permanganate. Synthesis of one-carbon dehomologated carbonyl compounds from enamines

Treatment of beta,beta-disubstituted enamines with potassium permanganate supported on neutral alumina leads to a mild and selective oxidative cleavage reaction which produces ketones and formamides. The ketones can be isolated in high yield and purity by a simple workup procedure. The oxidizing agent is selective and preferentially oxidizes an enamine carbon-carbon double bond in the presence of a distal carbon-carbon double bond. Other functional groups unaffected by this reagent include nitriles, secondary alcohols, and alkynes allowing a wide range of potentially selective oxidations. (C) 1997, Elsevier Science Ltd.