2- Alkyl thiazoles, nitration

Thiazole Nitration Sulfonation Brominadon Mercuration Alkylation... 

More quantitative results are available for the nitration of alkyl-thiazoles Dou et al. (373) determined the reactivity, relative to benzene, of the nitration site of various mono- and dialkylthiazole by competition experiments (Table 1-53). 

The most widely studied electrophilic substitution reactions are haloge-nation and nitration. Two main types of substrates are possible alkyl-thiazoles and arylthiazoles. 

Imidazole is much more reactive towards nitration than thiazole, snbstitution taking place via the salt, as does nitration of alkyl-thiazoles. Thiazole itself is nntonched by nitric acid/oleum at 160 °C, but methyl-thiazoles are sufficiently activated to undergo substitntion, the typical regioselectivity being for formation of more 5-nitro than 4-nitro derivatives the 2-position is not attacked 4,5-dimethylimidazole is resistant to nitration. The much less reactive oxazoles do not nndergo nitration. 

Thiazole, 2-acetylamino-4-methyl-alkylation, 6, 256 Thiazole, 2-acylamino-4-hydroxy-synthesis, 6, 297 Thiazole, 5-alkoxy-cleavage, 6, 289 synthesis, 6, 302 Thiazole, 2-alkyl-A7-alkylation, 6, 253 hydrogen exchange, 6, 276 methylation, 6, 253 quatemization, 6, 253-254 reactions, S, 88 Thiazole, 4-alkyl-A7-alkylation, 6, 253 methylation, 6, 253 quatemization, 6, 253-254 Thiazole, 5-alkyl-A7-alkylation, 6, 253 methylation, 6, 253 Thiazole, 2-alkylamino-tautomerism, 6, 248 Thiazole, 4-alkyl-2,5-dimethyl-quatemization, 6, 253-254 Thiazole, 2-alkylthio-reactions, S, 103 rearrangement, 5, 103 6, 291 Thiazole, 3-allyl-4-hydroxy-2-imino-synthesis, 6, 297 Thiazole, 2-allyloxy-rearrangement, 6, 289 Thiazole, 2-amino-diazo coupling, 6, 257 nitration, 6, 255... 

Tmidazo[2,l-Z)]thiazole has been shown by n.m.r, spectroscopy to protonate on the N-atom of the imidazole ring, whilst the mass spectra of some 2-alkyl-substituted imidazo[2,l-6]thiazoles have been correlated with their structures. Compound (69) is brominated in the vacant imidazole ring position by bromine in acetic acid or with sodium hypobromite, but bromination with bromine in chloroform occurs preferentially in the vacant a-position of the furan ring, and in this case a mixture of mono- and di-bromo-compounds is obtained. Compound (69) undergoes the Mannich reaction preferentially in the vacant imidazole ring position the products undergo further substitution e.g. nitration) in the a-position of the furan ring. ... 

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