Hydrochloric Acid → Rofecoxib

Beteiligte Stoffe

Reaktionsschritte

To a solution of phenylacetic acid (27.4 g, 201 mmol) and 2-bromo-1-(4-(methylsulfonyl)phenyl)ethanone (Example 9, Step 1) (60 g, 216 mmol, 1.075 eq.) in acetonitrile (630 mL) at 25° C. was added slowly triethylamine (30.8 mL, 1.1 eq.). The mixture was stirred for 20 min. at room temperature and then cooled in an ice bath. DBU (60.1 mL, 3 eq.) was slowly added. After stirring for 20 min. in the ice bath, the reaction was complete and the mixture was acidified with 1N HCl (color changes from dark brown to yellow). Then 2.4 L of ice and water were added, stirred for a few minutes, then the precipitate was filtered and rinsed with water (giving 64 g of crude wet product). The solid was dissolved in 750 mL of dichloromethane (dried over MgSO4, filtered) and 300 g of silica gel was added. The solvent was evaporated to near dryness (silica gel a bit sticky) and the residue was applied on top of a silica gel plug (sintered glass funnel) eluted with 10% EtOAc/CH2 Cl2, giving after evaporation of the solvent and swish in ethyl acetate, 36.6 g (58%) of the title compound.

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