4- Substituted 2-aminothiazoles, sulfonation

In fuming sulfuric acid (20% oleum) 2 aminothiazole (16. 27. 375. 389) and 2-amino-4-methylthiazole (374. 390) are sulfonated in the 5-position. When this position is substituted as in 2-amino-5-methyl-thiazole (27, 391) very small amounts of 4-sulfonation occur. 

Some 5-substituted 2-aminothiazoles with alkyl (15, 173, 175, 224, 366, 396), ester (173, 184, 220), aryl (115, 265, 396, 414), a-naphthyl (463), sulfur and sulfones derivatives (329, 373), isonitrosomethyl (772), and chloro groups were synthetized from the corresponding a-haloaldehyde and thiourea in lower yield (Table 11-14). 

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