Open Access5‐aminothiazolium salts as potential cyclic azomethine ylides: Base‐induced cycloaddition reactions with aryl, alkyl, and benzoyl isothiocyanates
Author(s) -
Touimi Benjelloun Adile,
Morel Georges,
Marchand Evelyne
Publication year - 2000
Publication title -
heteroatom chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.283
H-Index - 42
eISSN - 1098-1071
pISSN - 1042-7163
DOI - 10.1002/(sici)1098-1071(2000)11:1<16::aid-hc4>3.0.co;2-f
Subject(s) - chemistry , mesoionic , aryl , moiety , medicinal chemistry , alkyl , isothiocyanate , regioselectivity , cycloaddition , thiazole , sydnone , alkylation , heteroatom , organic chemistry , ring (chemistry) , catalysis
Reactions of the in situ generated thiazoles 2 with aryl and alkyl isothiocyanates appear to be totally regioselective and give the unexpected 5‐(phenylthio)imidazolium‐4‐thiolates 3 . Such rapid interconversion of mesoionic compounds is explained by a 1,3‐dipolar addition to the C=N bond of the heterocumulene followed by tBuNCS elimination. Similar interactions with benzoyl isothiocyanate exclusively proceed on the C=S unsaturation of the heteroallene moiety and produce the 4‐(phenylthio)thiazolium‐5‐amidines 12 . Structural assignment of isolated imidazoles and thiazoles is based on 13 C NMR data and chemically confirmed by the NaBH 4 reduction of the alkylated derivatives 5 and 13 . Efforts to isomerize the starting mesoionic thiazole 2a without the use of tBuNCS are unsuccessful. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 10:16–26, 2000