With the rapid development and complex challenges of chemical substances, new drug synthesis pathways are usually the most effective.615-20-3,2-Chlorobenzothiazole,as a common compound, the synthetic route is as follows.
615-20-3, To a solution of 2-CHLOROBENZOTHIAZOLE (12.0 g, 70.7 MMOL) in concentrated H2SO4 (60 mL) was added HN03 (69percent solution, 6 mL) dropwise at 0°C for 20 min. The mixture was stirred at 5°C for 3h, poured into ice-water (150 mL). The precipitate was collected and washed with 5percent sodium bicarbonate and water, dried in VACUO.APOS;H NMR analysis showed the mixture contained 78percent 6-nitro-2-chlorobenzothiazole and 8percent 5-nitro-2- chlorobenzothiazole. Recrystallization from ethanol gave 6-nitro-2-chlorobenzothiazole as white crystalline solid (11 g, 72percent). 3.5 g of the solid was dissolved in refluxing ethanol-acetic acid (150: 15 mL), Iron powder was added in one portion.. The mixture was refluxed for 1.5h, filtered. The filtrate was concentrated in vacuo to half volume and neutralized with 10percent NaOH to pH 7.5, extracted with ethyl acetate. The organic phase was washed with brine, dried over magnesium sulphate and evaporated to give a residue, which was RECRYSTALLIZED from ethanol. Light purple crystals (2.5 g, 83percent) were obtained. Mp 160-164°C ; TLC single spot at Rf 0.27 (30percent EtOAc/hexane) ;APOS;HNMR (270 MHz, DMSO-d6) 5 7.58 (1H, d, J = 9.0 Hz, 4-H), 7.03 (1H, d, J = 2.0 Hz, 7-H), 6.77 (1 H, dd, J = 9.0, 2. 0 Hz, 5-H), 5.55 (2H, s, NH2). The mother liquor from the RECRYSTALLIZATION of nitration product was evaporated and subjected to iron powder reduction as described above. The crude product was purified with flash chromatography (ethyl acetate-DCM gradient elution) to give 2-CHLORO- benzothiazol-5-yl-amine as yellow solid. Mp 146-149°C ; TLC single spot at Rf 0.52 (10percent EtOAc/DCM) ;APOS;HNMR (270 MHZ, DMSO-d6) 8 7.63 (1 H, d, J = 8. 6 HZ, 7-H), 7.05 (1 H, d, J = 2.3 Hz, 4-H), 6.78 (1 H, dd, J = 8.6, 2.3 Hz, 6-H), 5.40 (2H, s, NH2).
As the paragraph descriping shows that 615-20-3 is playing an increasingly important role.
Reference：
Patent; STERIX LIMITED; WO2004/37251; (2004); A1;,
Thiazole | C3H3NS – PubChem
Thiazole | chemical compound | Britannica