To a stirred solution of N,N-dimethyl-2-(7-nitro-2H-benzo[b][1,4]thiazin-4(3H)-yl)ethanamine (100 mg, 0.374 mmol) in dichloromethane (5 mL) under argon was added phenyl carbonochloridate (0.094 mL, 0.748 mmol). The resulting mixture was stirred at room temperature. A precipitate was observed, and triethylamine (3 drops) was added to aid dissolution (reaction turned clear). The mixture was then stirred over the weekend. The clear yellow mixture was then diluted with water and sodium carbonate and then extracted with dichloromethane (3×). The combined organics were dried, filtered, concentrated, and then chromatographed in ethyl acetate, giving the desired product (139 mg, 100%). 1H NMR (DMSO-d6) δ 7.84-7.74 (m, 2H), 7.39-7.31 (m, 2H), 7.23-7.16 (m, 1H), 7.03-6.93 (m, 3H), 3.85-3.78 (m, 3H), 3.73-3.65 (m, 2H), 3.55-3.50 (m, 1H), 3.09, 2.97 (2s, 3H), 3.09-3.05 (m, 2H); MS-EI: (m/z, %) 373 (M+, 4), 209 (31), 179 (100), 151 (28).
