Sodium Hydroxide → 4-[(6-Ethynylbenzo[b]thien-2-yl)sulfonyl]-2-[N-methylcarbamoyl)-1-[(6-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridin-2-yl)carbonyl]piperazine

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Reaction Steps

In a mixed solvent of tetrahydrofuran (0.5 ml) and methanol (0.5 ml) was dissolved 2-(N-methylcarbamoyl)-1-[(6-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridin-2-yl)carbonyl]-4-[(6-trimethylsilylethynylbenzo[b]thien-2-yl)sulfonyl]piperazine (90 mg), followed by the addition of a 1N aqueous solution (0.3 ml) of sodium hydroxide. The resulting mixture was stirred at room temperature for 2 hours. The reaction mixture was made weakly acidic with a saturated aqueous solution of ammonium chloride and then made weakly alkaline with a saturated aqueous solution of sodium bicarbonate. The solution was extracted (four times) with methylene chloride. The organic layers were combined, dried over anhydrous sodium sulfate and distilled under reduced pressure to remove the solvent. The residue was purified by preparative thin-layer chromatography (methanol:methylene chloride=1:9). Similar reaction and post treatment were repeated three times and the purified products were combined, followed by purification through Sephadex LH-20 (elution with methanol). The amorphous substance thus obtained was dissolved in methylene chloride. Hexane was added dropwise to the resulting solution, whereby the title compound (82 mg) was obtained as a light gray solid.

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