[Step 2] To a solution of 2-benzoyl-4-bromo-N-(2-hydroxypentyl)-N-(4-methanesulfonylbenzyl)benzamide (2.7 g) in DMSO (27 ml) was added triethylamine (11 ml), and pyridine sulfur trioxide complex (6.2 g) was added to the mixture at room temperature. The mixture was stirred for 1 hr. and added to water. 10% Hydrochloric acid was added to acidify the aqueous layer and the mixture was extracted with ethyl acetate. The organic layer was washed with water, saturated aqueous sodium hydrogen carbonate, water and saturated brine, and dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure to give 2-benzoyl-4-bromo-N-(4-methanesulfonylbenzyl)-N-(2-oxopentyl)benzamide (2.2 g).
