Iodine → 8,8a-dihydro-1H-azirino[1,2-b][1,2]benzothiazine 3,3-dioxide

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Reaction Steps

Iodine (6.51 g, 26.7 mmol) was added in one portion to a solution of 2-(2-propenyl)benzenesulfonamide (2.53 g, 12.8 mmol) in N2-degassed dichloromethane (125 mL) containing potassium carbonate (7.09 g, 51.3 mmol). After stirring for 20 min, water (50 mL, containing 2 g of sodium metabisulfite) was carefully added. The layers were separated and the aqueous layer was extracted with dichloromethane (25 mL). The combined organic layers were washed with water (25 mL). To the combined organic layers were added methanol (50 mL) and 0.25 N potassium carbonate in 70% aqueous methanol. After stirring for 10 min, sodium metabisulfite (100 mg) was added to discharge the color. The volatile organic solvents were removed in vacuo. The residue was partitioned between dichloromethane (100 mL) and additional water (30 mL). The aqueous layer was extracted with dichloromethane (25 mL). The combined organic layers were dried (magnesium sulfate) and concentrated in vacuo to provide 8,8a-dihydro-1H-azirino[1,2-b][1,2]benzothiazine 3,3-dioxide as a pale yellow oil which solidified (2.25 g, 90%): LCMS (pos. ion spectrum) m/z 237 (M+H+CH3CN).

Provenance & Evidence