To a solution of 2-(4-bromo-2,6-dimethylphenyl)-5-(hydroxypyridin-2-ylmethyl)-3-methoxycyclopent-2-enone (7.2 g, 17.9 mmol) in dichloromethane (200 ml) at 0°C. is added triethylamine (7.0 ml, 53.8 mmol) dropwise, then methanesulfonyl chloride (6 ml, 53.8 mmol). The reaction mixture is allowed to warm to room temperature, then is stirred overnight and quenched with ice cold water. The organic phase is separated and the aqueous phase is extracted with ethyl acetate (100 ml×3). The combined organic fractions are concentrated in vacuo and the residue is re-dissolved in methanol (250 ml) and stirred for 10 minutes. To this suspension is then added potassium carbonate (8.1 g, 58.7 mmol), and the reaction mixture is stirred for 4-5 hours at 25-30°C. Volatile solvents are removed under vacuum and the crude product is diluted with distilled water and extracted with ethyl acetate (150 ml×3). The combined organic fractions are washed with distilled water, brine, then dried over sodium sulfate, filtered and the filtrate is concentrated in vacuo. The crude product is purified by flash column chromatography to afford 2-(4-bromo-2,6-dimethylphenyl)-3-methoxy-5-[1-pyridin-2-ylmethylidene]cyclopent-2-enone.
