Methanol → 3-oxo-3,4-dihydro-2H-benzo[1,4]thiazine-6-carboxylic acid {1-[2-(7-hydroxy-quinoxalin-2-yloxy)-ethyl]-piperidin-4-yl}-amide

Participants

Reaction Conditions

Reaction Steps

A solution of 1M boron tribromide in dichloromethane (2.93 mL, 2.93 mmol, 8.0 eq) is added at 0° C. to a stirred solution of 3-oxo-3,4-dihydro-2H-benzo[1,4]thiazine-6-carboxylic acid {1-[2-(7-methoxy-quinoxalin-2-yloxy)-ethyl]-piperidin-4-yl}-amide (190 mg, 0.37 mmol, 1.0 eq) in dichloromethane (2.5 mL). The reaction mixture is stirred at 0° C. for 30 minutes and then at 40° C. for 24 hours. The reaction mixture is cooled down to 0° C. before the addition of methanol (1 mL). Solvents are evaporated and the crude is taken in water (10 mL), the pH is adjusted to 10 by the addition of 1N sodium hydroxide aqueous solution and the resulting aqueous layer is extracted with diclhoromethane (3×10 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 3-oxo-3,4-dihydro-2H-benzo[1,4]thiazine-6-carboxylic acid {1-[2-(7-hydroxy-quinoxalin-2-yloxy)-ethyl]-piperidin-4-yl}-amide as a white lyophilizated powder (28 mg, 30% yield).

Provenance & Evidence