Aminobenzothiazoles. III. Tautomerism and unsaturation of the aminothiazole system was written by Hunter, R. F.. And the article was included in Journal of the Chemical Society in 1926.Application of 40172-65-4 This article mentions the following:
1-Aminobenzothiazole (I) and MeI at 100掳 for 5 hrs. give 1-imino-2-methyl-1,2-dihydrobenzothiazole (II), m. 123掳, whose constitution was established by its synthesis from the dibromide, orange-red, sinters and softens at 125掳 (prepared from PhNMeC(:S)NH2 and Br in CHCl3). There is also probably formed some 1-methylaminobenzothiazole (III), m. 138掳, which was prepared from the tetrabromide (IV), scarlet, m. 65-7掳 (decomposition) (prepared from PhNHC(:S)NHMe and Br in CHCl3). Ethylation of I gave the 2-Et derivative corresponding to II, pale yellow, m. 85掳, likewise prepared from its tetrabromide, vermilion-orange, m. 160-1掳 (decomposition). Acetylation of I gives almost quant. the 1-Ac derivative, m. 186掳, also obtained by the reduction of its tetrabromide, orange-red, m. 137-9掳; the isomer could not be obtained pure. II in CHCl3, treated with excess of 20% Br in CHCl3, gives a tribromide, orange, becomes white without melting at 245掳. IV, exposed to the air for 20 hrs., loses Br and forms the orange-yellow dibromide, sinters 136掳, chars at 191掳; it loses more Br on further exposure. IV in absolute EtOH, after dilution with H2O and concentration, gives a mixture of Br- and Br2-substitution products, which could not be separated 1-Imino-2-acetyl-1,2-dihydrobenzothiazole (V), m. 118-20掳, results by the reduction with H2SO3 of the dibromide (VI), orange, m. 130-2掳 (from the labile form of PhNHC(:S)NH2); a 2nd form, purplish red, sinters 160掳, m. 173掳 (decomposition), which is very stable in air and is more slowly reduced by SO2, was also isolated. The HBr salt, dark chocolate prisms, turns orange 178掳 and m. 180掳 (decomposition). Hydrolysis of V gives I. 1-Benzoylaminobenzothiazole tetrabromide, orange-yellow, becomes colorless and loses Br at about 185掳; boiling in EtOH gives 5-bromo-1-benzoylaminobenzothiazole, m. 226掳. I, diazotized and treated with 尾-C10H7OH, gives benzothiazole-1-azo-尾-naphthol, deep purple-red, m. 146掳; it dyes cotton a fugitive shade of yellow; reduction gives I. 1-Aminoazobenzothiazole, cream-white, m. 135掳; HCl salt, yellow, m. 232掳 (decomposition). With NaOCl this gives a dark purple compound, m. 156-8掳. EtNO2 in EtOH gives 蠄-aminobenzothiazole, pale yellow, m. about 127掳, isolated as the HCl salt, ruby-red or deep orange, m. 239-40掳. 蠄-Amino-3-toluthiazole HCl salt, ruby-red, sinters 145掳, changes color at 145掳; the corresponding 5-derivative, red, sinters 130掳, softens about 150掳. These facts establish the mobility of I. 5-Bromo-1-amino-benzothiazole dibromide (VII), orange-red, softens 80-2掳, from p-BrC6H4NHC(:S)NH2 and Br in CHCl3; H2SO3 and NH3 convert it into the free thiazole, m. 211掳. 1-Acetylaminobenzothiazole hexabromide, orange-red, turns yellow at 130掳, loses Br at 140掳 and becomes colorless at about 160掳; in EtOH it gives 5-bromo-1-acetylaminobenzothiazole, m. 223掳. VI in EtOH gives 5-bromo-1-imino-2-acetyl-1,2-dihydrobenzothiazole, m. 199-200掳. Hydrolysis of each of these gives 5-bromo-1-aminobenzothiazole. 1-Amino-3-methylbenzothiazole, m. 136掳, results by reduction of the dibromide, orange, m. 110掳 (decomposition), which in turn is formed from o-MeC6H4NHC(:S)NH2 and Br in CHCl3; the latter is unstable and loses Br in the air; in EtOH it gives the HBr salt, turns yellow at 260掳, chars about 290掳, of bromo-1-amino-3-methylbenzothiazole, m. 212掳. 1-Amino-5-methylbenzothiazole, m. 142掳, is formed from the dibromide-HBr, orange-red, m. 134掳 (decomposition); with EtOH the latter yields a Br substitution product, m. 210掳. 1-Amino-4-methylbenzothiazole, m. 145掳, from the tetrabromide, orange-red, m. about 250掳 (decomposition) after undergoing a series of color changes. The 3,5-di-Me derivative, m. 116掳; its tetrabromide, red, does not m. 250掳 and is very unstable, losing Br and becoming colorless on exposure to the air for 0.5 hr. 2-Amino-尾-naphthothiazole, sinters 220掳, m. 235-7掳; tetrabromide, orange, does not m. 260掳; the corresponding 伪-derivative, sinters 230掳, m. 249-51掳; tetrabromide, yellow, m. 165掳 (decomposes). I dibromide in nearly boiling H2O gives VII. In the experiment, the researchers used many compounds, for example, Naphtho[1,2-d]thiazol-2-amine (cas: 40172-65-4Application of 40172-65-4).
Naphtho[1,2-d]thiazol-2-amine (cas: 40172-65-4) belongs to thiazole derivatives. The thiazole ring has been identified as a central feature of numerous natural products, perhaps the most famous example of which is epothilone. There are numerous natural products that possess a thiazole ring with broad pharmacological activities. Thiamine, also known as vitamin B1, possesses a thiazole ring linked with 2-methylpyrimidine-4-amine as hydrochloride salt.Application of 40172-65-4
Referemce:
Thiazole | C3H3NS – PubChem,
Thiazole | chemical compound | Britannica