Triazole-thiones, quaternization

The mesomeric effect of the C=S linkage is very pronounced and is responsible for the facile quaternization of heterocyclic N-alkylated thiones (159) this effect is operative even when such a shift does not increase the aromaticity of the ring. Thione derivatives of pyridazine, benzothiazole, quinazoline, 1,3-thiazine, triazole,and isoindole are examples of compounds which readily form quaternary salts. 

Quaternization of thiones or thiols proceeds successively through alkylation to methylthio compounds to attack on annular N centres (S9JCS3799. 6ila(641)94, 67JOC224s) to triazolium salts or mesoionic compounds. However, 3,5-bis(methylthio)-l-phenyl-l,2,4-triazole could not be quaternized (54CI(L)1458). 

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See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

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