Sodium Bicarbonate → 6-(((1-(2-(7-methoxy-2-oxoquinoxaline-1-(2H)-yl)ethyl)piperidin-4-yl)amino)methyl)-2H-1,4-benzothiazine-3(4H)-one

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Reaction Steps

To 3.0 mL of methanol solution containing 0.20 g of 1-(2-(4-aminopiperidin-1-yl)ethyl)-7-methoxyquinoxalin-2(1H)-one, 0.13 g of 3-oxo-3,4-dihydro-2H-1,4-benzothiazine-6-carbaldehyde, 38 μL of acetic acid and 83 mg of sodium cyanoborohydride were added at room temperature and stirred at the same temperature for 4 hours. To the mixture, chloroform and aqueous saturated sodium hydrogen carbonate solution was added to be adjusted to pH 9.5, the organic layer was separated, and the aqueous layer was extracted with chloroform. The organic layer and extracts were combined, washed sequentially with water and aqueous saturated sodium chloride solution, dried over anhydrous magnesium sulfate, and the solvent was removed under reduced pressure. The residue thus obtained was purified by silica gel column chromatography [eluent; chloroform:methanol=20 3], to give 60 mg of 6-(((1-(2-(7-methoxy-2-oxoquinoxaline-1-(2H)-yl)ethyl)piperidin-4-yl)amino)methyl)-2H-1,4-benzothiazine-3(4H)-one a pale yellow solid.

Provenance & Evidence