To a mixture of (2R)-2-[2-(3,4-dichlorophenyl)morpholin-2-yl]ethanol (25 g, 90.3 mmol) and acetonitrile (125 ml), triethylamine (27.4 g, 271 mmol) was added under a nitrogen stream, the resulting mixture was cooled to 0-5° C., then a solution of 3,4,5-trimethoxybenzoyl chloride (21.24 g, 92.1 mmol) in toluene (100 ml) was further added dropwise at below 10° C., and then the mixture was stirred at 0-5° C. for one hour. After completion of the reaction, toluene (150 ml), water (125 ml) and concentrated hydrochloric acid (25 ml) were added to the reaction mixture, and the resulting mixture was partitioned. The separated organic layer was washed successively with a saturated aqueous solution of sodium hydrogencarbonate and water, and concentrated to afford (2R)-2-[2-(3,4-dichlorophenyl)-4-(3,4,5-trimethoxybenzoyl)morpholin-2-yl]ethanol (44.4 g) as an oil.
