5-Aminoisoxazole → 4-(2-cyano-4-(trifluoromethyl)phenyl)-N-(isoxazol-5-yl)-3,4-dihydro-2H-benzo[b][1,4]oxazine-7-sulfonamide

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Reaction Steps

A round bottom flask was charged with perfluorophenyl 4-(2-cyano-4-(trifluoromethyl)phenyl)-3,4-dihydro-2H-benzo[b][1,4]oxazine-7-sulfonate (44.1 mg, 0.080 mmol), isoxazol-5-amine (10.1 mg, 0.12 mmol, Matrix Scientific, Columbia, S.C.) and THF (1 mL) to give a clear, colorless solution. The flask was cooled in a dry ice-acetone bath for 5 min, then lithium bis(trimethylsilyl)amide (1M in THF) (168 μl, 0.168 mmol) was added dropwise over 30 s to give a light-yellow solution. After 10 min, the flask was lowered into an ice bath for 45 min. Glacial acetic acid (1 drop) was added, and the mixture was concentrated under a vacuum. The product was purified by chromatography on silica gel (12 g column with 0 to 10% MeOH/DCM) to give 4-(2-cyano-4-(trifluoromethyl)phenyl)-N-(isoxazol-5-yl)-3,4-dihydro-2H-benzo[b][1,4]oxazine-7-sulfonamide (25.2 mg, 0.056 mmol) as a light-yellow solid. 1H NMR (400 MHz, DMSO-d6) δ ppm 12.18 (br. s., 1 H), 8.42 (d, J=2.1 Hz, 1 H), 8.34 (d, J=2.0 Hz, 1 H), 8.11 (dd, J=2.0, 8.9 Hz, 1 H), 7.76 (d, J=8.6 Hz, 1 H), 7.30 (d, J=2.2 Hz, 1 H), 7.23 (dd, J=2.2, 8.7 Hz, 1 H), 6.80 (d, J=8.6 Hz, 1 H), 5.77 (d, J=1.9 Hz, 1 H), 4.40-4.35 (m, 2H), 3.89-3.86 (m, 2 H). m/z (ESI) 451.4 (M+H)+.

Provenance & Evidence