Pfltzner-Moffatt oxidation

Pfltzner-Moffatt oxidation (1, 304-307 2, 162 3, 121). The oxidation of the alcohol 1 under the conditions of Moffatt, using DMSO, DCC, TFA, and pyridine, was accompanied by dehydration to the conjugated diene. Substitution of TFA and pyridine by 857o phosphoric acid gave 2 in 80% yield, This product was converted by conventional methods into tranj-damascone (5). ... 

The widely used Moifatt-Pfltzner oxidation works with in situ formed adducts of dimethyl sulfoxide with dehydrating agents, e.g. DCC, AcjO, SO], P4O10, CCXTl] (K.E, Pfitzner, 1965 A.H. Fenselau, 1966 K.T. Joseph, 1967 J.G. Moffatt, 1971 D. Martin, 1971) or oxalyl dichloride (Swem oxidation M. Nakatsuka, 1990). A classical procedure is the Oppenauer oxidation with ketones and aluminum alkoxide catalysts (C. Djerassi, 1951 H. Lehmann, 1975). All of these reagents also oxidize secondary alcohols to ketones but do not attack C = C double bonds or activated C —H bonds. 

Pfltzner and Moffatt report the interesting finding that an equatorial 11 a-hydroxy-steroid is oxidized readily by the DMSO-DCC combination whereas the 11 /3-epimer is inert under the same conditions. The situation is thus the reverse of that found in chromic acid oxidation (Eschenmoser). The authors offer an explanation based on a suggested mechanism for the oxidation. 

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