Nitraminothiazoles

The nitro group increases the acidity of the hydrogen born by the exocyclic nitrogen, and alkylation of 2-nitraminothiazole with diazomethane is possible (87), The formed 2-(A -methylnitramino)-thiazole also may be obtained from the reaction of 2-nitraminothiazole with dimethylsulfate in basic medium (194). 

2-Nitraminothiazole. treated for 12 hr with 96% sulfuric acid, gives 2-amino-5-nitrothiazole (194). The mechanism of this rearrangement is not yet quite resolved even for nitraminobenzene derivatives (617). The series of kinetic determinations and appropriate labeling performed by Toth et al. provide, however, precious hints for this difficult problem (1578. 1579). 

Not many examples of this class of compounds have been reported. They are prepared by the action of sodium azide on 2-diazonium salts of 2-aminothiazole (590, 597, 598). 

Sulfonation by oleum occurs as expected on C-5 (598). The same position is reactive toward bromination, thiocyanation, and nitration 

---

Nitraminothiazoles are sufficiently acidic to be alkylated by diazomethane the methyl substituent is introduced on the exocyclic nitrogen (194). When sulfathiazole is methylated with diazomethane in ether, a mixture of ring-methylated and amino-methylated products is obtained, the ratio being 30 70 (85). With anion 31 (R = p-NO CsH4SO -) the ratio becomes 15 85 (195). 

In aniline derivatives (458) the mechanism of this reaction is still not fully settled (459-461). However, the latest results seem to favor a pathway that, applied to 2-nitraminothiazole, would give Scheme 138, where the key step is the formation of a radical ion (223). Reexamination of the original reports on this reaction (16, 374, 378. 462) with EPR and Chemically Induced Dynamic Nuclear Polarisation techniques could be fruitful. 

Crvsts mp 2 71.5—272°. Can be prepd by treating 2-nitraminothiazole either with dimethyl sulfate or ethereal diazomethane as described in Ref 2... 

---