Direct amination of derivatives of benzothiazole was written by Vel’tman, R. P.. And the article was included in Zhurnal Obshchei Khimii in 1956.Application In Synthesis of Benzothiazole-5-carboxylic acid This article mentions the following:
Heating 6.4 g. 2-bromo-5-nitroaniline and 65 ml. 85% HCO2H on steam bath 3 hrs. gave 89% 1-formylamino-2-bromo-5-nitrobenzene, m. 202-3° (from EtOH); with Na2S2 this gave 5-nitrobenzothiazole (cf. Fries and Wolter, C.A. 31, 14051). This reduced with SnCl2-HCl to 5-aminobenzothiazole-H2O, 60%, m. 76°. Oxidation of 5-methylbenzothiazole with KMnO4 gave 5-carboxybenzothiazole, m. 261-2° (from H2O); Et ester, m. 106-8° (from aqueous EtOH). The 5-substituted benzothiazoles were refluxed with equimolar amounts of NH2OH.HCl and aqueous NaOH for 0.5-4 hrs. (the NO2 derivative failed to react after a prolonged period). The usual treatment yielded the following products: 2-amino-5-methylbenzothiazole, m. 171-2°, 68%, from 5-methylbenzothiazole; 2,5-diaminobenzothiazole, m. 175°, 72%, from 5-aminobenzothiazole; 2-amino-5-carboxybenzothiazole, decompose 300°, 64%, from 5-carboxybenzothiazole. The 5-carbethoxy derivative failed to react as did the NO2 derivative 2-Amino-5-benzothiazolecarboxylic acid gave the Et ester, m. 200-1°. In the experiment, the researchers used many compounds, for example, Benzothiazole-5-carboxylic acid (cas: 68867-17-4Application In Synthesis of Benzothiazole-5-carboxylic acid).
Benzothiazole-5-carboxylic acid (cas: 68867-17-4) belongs to thiazole derivatives. The thiazole ring is notable as a component of the vitamin thiamine (B1). Electrophilic attack at nitrogen depends on the presence of electron density at nitrogen as well as the position and nature of substituent linked to the thiazole ring.Application In Synthesis of Benzothiazole-5-carboxylic acid
Referemce:
Thiazole | C3H3NS – PubChem,
Thiazole | chemical compound | Britannica