HCID 18670265, compound → (10-methoxymethyl-10H-pyrazino[2,3-b][1,4]benzothiazin-8-yl)methyl ketone

Participants

Reaction Steps

Into a solution of 16 g of 10-(methoxymethyl)-10H-pyrazino[2,3-b][1,4]benzothiazine-8-carboxaldehyde in 200 ml of tetrahydrofuran was dropped at −78° C. 60 ml of a 1.4 M solution of methyllithium in diethyl ether. Next, the resulting mixture was heated to room temperature over 2 hours. The reaction mixture was poured into ice-water and extracted with ethyl acetate. The organic layer was washed with a saturated aqueous solution of sodium chloride and dried over anhydrous magnesium sulfate. After distilling off the solvent under reduced pressure, 16 g of a yellow oily substance was obtained. To a solution of 16 g of this oily substance in dichloromethane (300 ml) was added 100 g of manganese dioxide and the resulting mixture was stirred at room temperature for 17 hours. After the completion of the reaction, the manganese dioxide was filtered off. The filtrate was concentrated and the residue thus obtained was purified by silica gel column chromatography (eluted with n-hexane/ethyl acetate) to thereby give 9. 4 g of the title compound. as yellow. crystals.

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