- Synthesis, oxidation and dehydrogenation of cyclic N,O- and N,S-acetals. Part III. [1,2] Transformation of N,O-acetals: 3-Acyl-1,3,4-oxadiazolines
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(Chemical Equation Presented) Various aldehyde and ketone acylhydrazones are synthesized and, under acylating conditions, cyclized into 3-acyl-1,3,4-oxadiazolines. The scope and limitations of these cyclizations and the possible side reactions (e.g. formation of the open-chain N,O-acylhydrazinocarbinols) are dissected. For the first time, simple, convenient and efficient dehydrogenations of 3-acyl-1,3,4-oxadiazolines to oxadiazoles by treatment with potassium permanganate, or more conveniently, with ammonium cerium(IV) nitrate (CAN) are presented. CAN oxidation of 2,2-disubstituted 3-acyl-1,3,4-oxadiazolines, as well as that of aldehyde diacylhydrazones (open-chain isomers of 2,5-disubstituted 3-acyl-1,3,4- oxadiazolines) regenerates the parent carbonyl compounds.
- Somogyi, Laszlo
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p. 1235 - 1246
(2008/09/18)
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