Chlorosulfonic acid → 4-(2-cyano-4-(trifluoromethyl)phenyl)-8-fluoro-3,4-dihydro-2H-benzo[b][1,4]oxazine-7-sulfonyl chloride

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Reaction Steps

To a vial charged with 2-(8-fluoro-2H-benzo[b][1,4]oxazin-4(3H)-yl)-5-(trifluoromethyl)benzonitrile (0.168 g, 0.521 mmol) was added DCM (2.085 ml). The resulting solution was cooled in an ice water bath prior to the addition of chlorosulfonic acid (0.139 ml, 2.085 mmol), faster than dropwise. After 30 mins the solution was added to ice water, and mixture was extracted 2× with EtOAc. The combined organics were dried with Na2SO4, filtered, and dried under reduced pressure. The crude material was purified with a 25 g SNAP column ramping EtOAc in heptane (0-25%, then isocratic at 25%, 10% DCM throughout) providing product as a white foam, 4-(2-cyano-4-(trifluoromethyl)phenyl)-8-fluoro-3,4-dihydro-2H-benzo[b][1,4]oxazine-7-sulfonyl chloride (0.127 g, 0.302 mmol, 57.9% yield). 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 3.91-3.99 (m, 2 H) 4.52 (dd, J=5.14, 3.67 Hz, 2 H) 6.42 (dd, J=9.19, 1.66 Hz, 1 H) 7.34 (dd, J=9.19, 6.75 Hz, 1 H) 7.60 (d, J=8.51 Hz, 1 H) 7.95 (dd, J=8.56, 1.81 Hz, 1 H) 8.07 (d, J=2.15 Hz, 1 H). m/z (ESI) 443.1 (M+Na)+.

Provenance & Evidence