Bromine → 2-Amino-5,5-dimethyl-5,6-dihydro-4H-benzothiazol-7-one

Participants

Reaction Steps

5,5-Dimethyl-cyclohexane-1,3-dione (201 g, 1.43 mol) and NaOAc (176 g, 2.14 mol) are suspended in AcOH (2 L) and Br2 (229 g, 1.43 mol) is added in dropwise while maintaining the reaction temperature between 15 and 20° C. After complete addition, the reaction is stirred at RT overnight. Thiourea (109 g, 1.43 mol) is added in portions and the reaction mixture is heated at 100° C. for 1 h. After cooling to RT, the AcOH is removed in vacuo and the resulting crude product is diluted with water (1 L) and neutralized with an aqueous saturated NaHCO3 solution. The resulting mixture is extracted with ethyl acetate (4×500 mL). The organic layer is washed with brine (500 mL), dried over anhydrous Na2SO4 and the solvent is evaporated in vacuo to give crude product. The crude product is washed with water (1.5 L) to yield 2-amino-5,5-dimethyl-5,6-dihydro-4H-benzothiazol-7-one (211 g, 75% yield).

Provenance & Evidence