Borane → 6-bromo-8-fluoro-5-methyl-3,4-dihydro-2H-benzo[b][1,4]oxazine

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Reaction Steps

An ice cold mixture of 6-bromo-8-fluoro-5-methyl-2H-benzo[b][1,4]oxazin-3(4H)-one (510 mg, 1.961 mmol) in Tetrahydrofuran (THF) (8 mL) was treated with borane 1M in THF (2.94 mL, 2.94 mmol) (1.5 eq) and then stirred at ambient temperature for 150 minutes. The mixture was cooled to 0° C. and then quenched slowly with 1N NaOH (5 mL×10). The mixture was extracted with ethyl acetate, washed with 1N NaOH, dried over sodium sulfate, filtered and then concentrated to afford 6-bromo-8-fluoro-5-methyl-3,4-dihydro-2H-benzo[b][1,4]oxazine (450 mg) as a light brown solid which was used without further purification. 1H NMR (400 MHz, CHLOROFORM-d) d=6.77 (d, J=10.1 Hz, 1 H), 4.28-4.25 (m, 2 H), 3.77 (br. s., 1 H), 3.52 (m, 2 H), 2.16 (s, 3 H); LC/MS (m/z) ES+=245.99 (M+1).

Provenance & Evidence