Chlorosulfonyl isocyanate → N-(1,1,3-trioxo-1,2,3,4-tetrahydro-1lambda6-benzo[1,2,4]thiadiazin-7-yl)-methanesulfonamide

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Reaction Conditions

Reaction Steps

Chloro-sulfonyl-isocyanate (1.7 mL, 19.6 mmol) was dissolved in nitroethane (10 mL) and chilled to −40° C. under nitrogen. N-(4-Amino-phenyl)-methanesulfonamide (Example 3b, 3g, 16.1 mmol) was added dropwise as a pre-dissolved solution in nitroethane (25 mL). The mixture was stirred at −40° C. for 15 min. Aluminum chloride (8 g, 60 mmol) was added and the mixture was heated at 110° C. for 30 min while stirring. The mixture was poured onto ice (150 g). Upon melting, the product was extracted into ethyl acetate (5×250 mL). The combined organic layers were dried over magnesium sulfate, filtered and concentrated in vacuo to afford the desired product, N-(1,1,3-trioxo-1,2,3,4-tetrahydro-1λ6-benzo[1,2,4]thiadiazin-7-yl)-methanesulfonamide (3.63 g, 12.46 mmol, 77% yield) as a beige solid. 1H NMR (400 MHz, DMSO-d6) δ 3.00 (3H, s), 7.22 (1H, d, J=8.5 Hz), 7.46 (1H, dd, J1=8.8 Hz, J2=2.7 Hz), 7.51 (1H, d, J=2.4 Hz), 9.92 (1H, s), 11.20 (1H, s).

Provenance & Evidence