Methyl 4-({4-[4-(2,2-dimethoxyethyl)anilino]-1-piperidinyl}carbonyl)benzoate (0.30 g, 0.703 mmol) was added to a pre-prepared mixture of sodium iodide (0.264 g, 1.76 mmol) and trichloro(methyl)silane (0.166 mL, 1.4 mmol) in anhydrous acetonitrile. The reaction was stirred at ambient temperature for 10 minutes. Dichloromethane was added and the reaction washed with 10% sodium thiosulfate solution, water and brine. The organic layer was dried over anhydrous magnesium sulfate, filtered and the solvent partially removed under vacuo. The aldehyde solution was used directly and treated with methanol (17 mL), acetic acid (0.043 mL, 0.75 mmol), N-(5-[(1R)-2-amino-1-hydroxyethyl]-2-hydroxyphenyl)methanesulfonamide (0.127 g, 0.516 mmol) followed by sodium cyanoborohydride (0.048 g, 0.764 mmol). The reaction was taken to dryness in vacuo, adsorbed onto silica and purified by flash chromatography on silica gel Merck-60 (eluant: 5:1 chloroform-methanol containing 1% ammonium hydroxide) to yield the title compound (0.127 g, 0.208 mmol).
