Step ii: Synthesis of 2-amino-5,6-dihydrobenzo[d]thiazol-7(4H)-one
To a 100 mL round bottom flask was added 2-bromo-1,3-cyclohexanedione (1.0 g, 5.23 mmol) and methanol (15 mL). Subsequently, thiourea (0.397 g, 5.23 mmol) and pyridine (0.412 g, 5.23 mmol) were added to the same flask. The reaction mixture was heated to reflux temperature and stirred for 4 hours. After completion of the reaction, the volatile solvent was removed by distillation under reduced pressure to give the crude product. The crude product was dissolved in water and stirred for 5 min to promote the formation of precipitate. The precipitate was collected by filtration and washed with distilled water to give the final 2-amino-5,6-dihydrobenzo[d]thiazol-7(4H)-one (0.8 g, 91% yield).
Product characterization data:
1H NMR (300 MHz, DMSO-d6): δ 8.12 (brs, 2H), 2.69 (t, 2H), 2.38 (t, 2H), 2.02 (m, 2H).
LC-MS (ESI): m/z 168.9 [M + H]+.
