Acetic Acid → 2H-1,4-benzoxazin-3(4H)-one

Participants

Reaction Steps

3-Oxo-3,4-dihydro-2H-benzo[1,4]oxazine-6-carbaldehyde (354 mg, 2.00 mmol, 1.0 eq) is added at room temperature to a stirred solution of 1-[2-(7-methoxy-quinoxalin-2-ylsulfanyl)-ethyl]-piperidin-4-ylamine (0.65 g, 2.00 mmol, 1.0 eq) in 1,2-dichloroethane (4 mL) and methanol (1 mL), followed by acetic acid (0.11 mL, 2.00 mmol, 1.0 eq) and sodium cyanoborohydride (160 mg, 2.6 mmol, 1.4 eq). After 15 hours stirring at room temperature, the reaction mixture is extracted with dichloromethane (3×20 mL) and a saturated sodium hydrogen carbonate aqueous solution (20 mL). The combined organic layers are dried over sodium sulfate, filtered and concentrated to give a residue that is purified by preparative HPLC to afford 6-({1-[2-(7-methoxy-quinoxalin-2-ylsulfanyl)-ethyl]-piperidin-4-yl}-amino)-methyl)-4H-benzo[1,4]oxazin-3-one as a white solid (500 mg, 52% yield).

Provenance & Evidence