3,4-dihydro-1H-2lambda6,3-benzothiazine 2,2-dioxide

Conditions: temp:80.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The title compound was prepared according to the method described in Bravo, R. D. et al. Synth. Commun. 2002, 32, 3675. A flask was charged with alpha-toluenesulfonamide (1 g, 5.8 mmol) and 1,3,5-trioxane (0.175 g, 1.9 mmol) in anhydrous dichloroethane (23 mL) and amberlyst 15H+ resin (3.7 g). The mixture was stirred at 80° C. overnight, after which the resin was filtered off and washed with methylene chloride. The organic solution was concentrated to afford a white solid (0.848 g, 79%). 1H NMR (d6-DMSO, 300 MHz) δ 7.41-7.37 (t, 1H, J=6.8 Hz), 7.30-7.24 (m, 2H), 7.19-7.16 (m, 1H), 7.12-7.09 (m, 1H), 4.42-4.40 (d, 2H, J=6.6 Hz), 4.35 (s, 2H). after which the resin was filtered off washed with methylene chloride The organic solution was concentrated