General procedure for the synthesis of benzo[d][1,2,3]thiadiazol-6-amine (5d) from 6-nitrobenzo[d][1,2,3]thiadiazole (5c): 6-nitrobenzo[d][1,2,3]thiadiazole (5c) (4.0 g, 22.1 mmol) was added to concentrated hydrochloric acid (100 mL). The reaction system was cooled to 0°C. Subsequently, tin(II) chloride dihydrate (SnCl2-2H2O) (15 g, 66.5 mmol) was dissolved in concentrated hydrochloric acid (80 mL) and added to the reaction system. The reaction was slowly warmed up to room temperature with continuous stirring for 5 hours. The reaction progress was monitored by thin layer chromatography (TLC). Upon completion of the reaction, the reaction mixture was diluted with water (50 mL), the pH was adjusted to 8-9 with saturated sodium bicarbonate (NaHCO3) solution, and then extracted with ethyl acetate (EtOAc) (3 x 150 mL). The organic phases were combined, dried over anhydrous sodium sulfate (Na2SO4) and concentrated under reduced pressure to obtain the crude product. The crude product was purified by column chromatography to afford the target product benzo[d][1,2,3]thiadiazol-6-amine (5d) (2.8 g, 82% yield).TLC conditions: 30% ethyl acetate/hexane (Rf: 0.2).1H NMR (200 MHz, CDCl3, δ ppm): 8.34 (d, J = 9.0 Hz, 1H), 7.14 (d, J = 2.2 Hz, 1H). J = 2.2 Hz, 1H), 6.93 (dd, J = 8.8 Hz, 2.0 Hz, 1H), 4.23 (br s, 2H). Mass spectrum (ESI): m/z 152.0 [M+H]+.
![6-nitrobenzo[d][1,2,3]thiadiazole](/CAS/20150408/GIF/29241-16-5.gif)
![benzo[d][1,2,3]thiadiazol-6-aMine](/CAS/20150408/GIF/41972-62-7.gif)