To a solution of 2-[4-(2-hydroxyethyl)piperazin-1-yl]-N-[2,4-bis(methylthio)-6-methyl-3-pyridyl]acetamide (93 mg, 0.251 mmol) in THF (2 ml) were added triethylamine (51 mg, 0.502 mmol) and 4-(dimethylamino)pyridine (3 mg, 0.025 mmol), and then dropped methanesulfonyl chloride (43 mg, 0.377 mmol) with ice-cooling. The mixture was stirred for 45 minutes. The reaction solution was concentrated in vacuo to provide crude 2-[4-(2-methanesulfonyloxyethyl)piperazin-1-yl]-N-[2,4-bis(methylthio)-6-methyl-3-pyridyl]acetamide.
