3144-06-7

37441-50-2

At room temperature, 4-chloro-1-butanesulfonamide (D5) (31 g, 200 mmol, 1.0 eq.) was dissolved in ethanol (500 mL), followed by the addition of sodium ethoxide (14.9 g, 220 mmol, 1.1 eq.). The reaction mixture was heated to reflux for 5 h. After completion of the reaction it was cooled to room temperature and concentrated under reduced pressure. The residual solid was fully extracted by adding dichloromethane to the residual solid and concentrated under reduced pressure after combining the organic phases. The resulting solid was ground with ether to afford tetrahydro-2H-1,2-thiazine 1,1-dioxide (D6) (18.7 g, 69% yield) as a light brown solid, which was used directly in the subsequent reaction without further purification.