Winterfeldt oxidation

When the autoxidation is carried out under basic conditions (t-BuOK/DMF), the initially formed ketoamides undergo intramolecular aldol-type condensation to give quinolinones in a preparatively useful process known as Winterfeldt oxidation [64]. 

The Witkop-Winterfeldt oxidation of indoles (formation of quinolones) ... 

Oxidative isomerization of vinylidenecyclopropanes gives dimethylenecyclopropane aldehydes using tetrapropylammonium perruthenate (TPAP)/4-methylmorpholine A-oxide (NMO) as a catalytic system. A Witkop-Winterfeldt oxidation with ozone has been reported to convert tetrahydropyridoindoles into pyrroloquinolones and cinnolines. Activation of phenol derivatives with a hypervalent iodine reagent has been reported to promote the formation of bicycUc and tricyclic products via a cationic cyclization process (Scheme 64). ... 

Zhang X, Jiang W, Sui Z (2003) Concise enantioselective syntheses of quinolactacins A and B through alternative Winterfeldt oxidation. J Org Chem 68 4523 526... 

The Winterfeldt oxidation (O2, r-BuOK) of carbolines such as the unsubstituted (37a) and aryl (37b) (Scheme 13) is known to give the pyrrolo[3,4-( ]quinoline-9-ones (38), via the attack on the amide function by the ketone enolate (path a). In the presence of the ester functionality (37c), however, the more readily formed malonic-type anion attacks the ketone according to an intramolecular Knoevenagel reaction leading to the new pyrrolo[2,3-c]quinoline-4-one system (39) (path... 

A-Alkylation of amides and amines and dehydrative -alkylation of secondary alcohols and a-alkylation of methyl ketones " have been carried out by an activation of alcohols by aerobic oxidation to aldehydes, with copper(II) acetate as the only catalyst. A relay race process rather than the conventional borrowing hydrogen-type mechanisms has been proposed for the aerobic C-alkylation reactions, based on results of mechanistic studies. A Winterfeldt oxidation of substituted 1,2,3,4-tetrahydro-y-carboline derivatives provides a convenient and efiflcient method for the synthesis of the corresponding dihydropyrrolo[3,2-fc]quinolone derivatives in moderate to excellent yields. The generality and substrate scope of this aerobic oxidation have been explored and a possible reaction mechanism has been proposed. Direct oxidative synthesis of amides from acetylenes and secondary amines by using oxygen as an oxidant has been developed in which l,8-diazabicyclo[5.4.0]undec-7-ene was used as the key additive and copper(I) bromide as the catalyst. It has been postulated that initially formed copper(I) acetylide plays an important role in the oxidative process. Furthermore, it has been postulated that an ct-aminovinylcopper(I) complex, the anti-Markovnikov hydroamination product of copper acetylide, is involved in the reported reaction system. Copper(I) bromide... 

Winterfeldt and Krohn have shown that the reaction of N,N-diethylhydroxylamine with DMAD proceeds through an iV-oxide intermediate (102), which gives rise to a mixture of products like the nitrone 104, the azetidine 105, and the hydroxylamine derivative 106 (Scheme 16). 

Winterfeldt has shown that the reaction of dimethyl sulfoxide with DMAD gives tetramethyl furantetracarboxylate (345), and it was suggested that this reaction may proceed through the intermediates 342, 343, and.344 (Scheme 52). The reaction of /-butylsulfenic acid with methyl propiolate, however, gives /3v -bis(/ra/is-carbomethoxy)divinyl sulfoxide (348) (Scheme 53). The penicillin S-oxide (349) is known to react with DMAD to give the adduct 352, and this reaction has been assumed to proceed through the sulfenic acid intermediate 350 (Scheme 54). ... 

Winterfeldt, E. and W. Krohn. 1969. Additionen an die Dreifachbindung. XII. Darstellung des N-Oxides eines nicht basischen vinylogen Urethans. Chem Ber 102 2336-2345. Winterfeldt, E. and W. Krohn. 1969. Additionen on die Dreifachbindung. XIII. Nitron-Addukte mit Acetylendicarbonsauredimethylester. Chem Ber 102 2346-2361. 

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