2-Aminooxazole → 4-(2-cyano-4-(trifluoromethyl)phenyl)-N-(oxazol-2-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 (INTERMEDIATE AB, 40.69 mg, 0.074 mmol), oxazole-2-amine (9.32 mg, 0.11 mmol, Ryan Scientific, Mt. Pleasant, 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) (155 μl, 0.155 mmol) was added dropwise over 30 s to give a light-yellow solution. After 5 min, the flask was lowered into an ice bath for 1 h. Additional portions of oxazole-2-amine (ca. 5 mg) and LHMDS solution (0.05 mL) were added in sequence. After an additional 45 min, glacial acetic acid (1 drop) was added. 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-(oxazol-2-yl)-3,4-dihydro-2H-benzo[b][1,4]oxazine-7-sulfonamide as a light-yellow solid. 1H NMR (400 MHz, DMSO-d6) δ ppm 11.86 (br. s., 1 H), 8.38 (d, J=2.1 Hz, 1 H), 8.05 (dd, J=1.8, 8.8 Hz, 1 H), 7.71 (d, J=8.6 Hz, 1 H), 7.59 (d, J=1.7 Hz, 1 H), 7.31 (d, J=2.1 Hz, 1 H), 7.26-7.17 (m, 2 H), 6.80 (d, J=8.5 Hz, 1 H), 4.36-4.27 (m, 2 H), 3.87-3.82 (m, 2 H). m/z (ESI) 451.4 (M+H)+.

Provenance & Evidence