Ethyl Acetate → 6-Amino-2,3-dihydro-1lambda6,2-benzothiazole-1,1-dione

Participants

Reaction Steps

To a solution of 6-amino-1,2-benzisothiazol-3(2H)-one-1,1-dioxide (7.0 g, 35 mmol, Preparation #1) in concentrated HCl (80 mL) was added zinc dust (19.0 g, 292 mmol), in portions over about 30 min while maintaining the temperature below about 70° C. The mixture was stirred at rt for about 3 h. The mixture was basified with a solution of saturated aqueous NaHCO3 (50 mL), then with solid NaHCO3 (pH=7). The mixture was added to EtOAc (100 mL), filtered and the filtrate was extracted with EtOAc (3×150 mL). The organic phases were combined, washed with brine (3×150 mL), dried over MgSO4, filtered and concentrated under reduced pressure to give a solid. The residue from filtration was triturated with EtOAc (2×200 mL) and filtered. The organic phases were combined, dried over MgSO4, filtered and concentrated under reduced pressure to give a solid. All the solids were dissolved in MeOH, combined and then concentrated to give 1,1-dioxo-2,3-dihydro-1H-1lambda*6*-benzo[d]isothiazol-6-ylamine (5.7 g, 88%): 1H NMR (DMSO-d6) δ 7.54 (s, 1H), 7.14 (d, J=8.5 Hz, 1H), 6.83 (dd, J=2.5, 2.0 Hz, 1H), 6.79 (d, J=1.5 Hz, 1H), 5.81 (s, 2H), 4.18 (s, 2H).

Provenance & Evidence