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Synthesis, oxidation and dehydrogenation of cyclic N,O ‐ and N,S ‐acetals. Part III. Transformation of N,O ‐acetals: 3‐acyl‐1,3,4‐oxadiazolines
Author(s) -
Somogyi László
Publication year - 2007
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570440603
Subject(s) - chemistry , dehydrogenation , aldehyde , cerium , ketone , potassium permanganate , ceric ammonium nitrate , medicinal chemistry , organic chemistry , catalysis , grafting , polymer
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.