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Compound B is prepared using the general method of Wierenga and Skulnick (Wierenga, W.; Skulnick, H. I. J. Org. Chem. (1979) 44: 310-311). n-Butyllithium (1.6 M in hexanes) is added to a cooled (−78° C.) solution of tetrahydrofuran (10 mL) containing ethyl hydrogen malonate (180 μL, 1.50 mmol) and 2,2′-bipyridyl (˜1 mg as indicator). The temperature of the reaction mixture is allowed to rise to ca. −5° C. during the addition of n-butyllithium. Sufficient n-butyllithium (2.8 mL, 4.48 mmol) is added until a pink color persists at −5° C. for 5-10 min. A solution of 2,4,5-trifluoro-3-methoxybenzoyl chloride (0.75 mmol, vide supra) in tetrahydrofuran (˜3 mL) is added in one portion to the reaction mixture that had been recooled to −78° C. The resulting mixture is allowed to warm to room temperature, diluted with ethyl acetate (50 mL), and quenched with a 1 M aqueous solution of hydrochloric acid. The organic layer is washed with a 5% aqueous solution of sodium bicarbonate (2×30 mL), followed by brine (2×50 mL), dried over sodium sulfate, and evaporated under reduced pressure to give the crude product. This material is purified by flash column chromatography (eluting with 20% v/v ethyl acetate in hexanes) to give pure B as a white solid. 1H NMR (300 MHz, CDCl3): (enol, predominant tautomer, ≧90%) 81.32 (t, JH-H=7.0 Hz, 3H, CO2CH2CH3), 4.02 (apparent t, JH-F=1.0 Hz, 3H, OCH3), 4.25 (q, JH-H=7.0 Hz, 2H, CO2CH2CH3), 5.79 (s, 1H, CH3C(OH)═CH—CO2CH2CH3), 7.39 (ddd, JH-F=11.0 Hz, 8.5 Hz, 6.5 Hz, 1H, aromatic), 12.68 (s, 1H, OH). 19F{1H} NMR (282 MHz, CDCl3): δ−146.8 (dd, JF-F=21.5 Hz, 10.5 Hz, 1F), −140.2 (dd, JF-F=21.5 Hz, 13.5 Hz, 1F), −131.3 (dd, JF-F=13.5 Hz, 10.5 Hz, 1F).

1. customhad been recooled to −78° C
2. customquenched with a 1 M aqueous solution of hydrochloric acid
3. washThe organic layer is washed with a 5% aqueous solution of sodium bicarbonate (2×30 mL)
4. dry with materialdried over sodium sulfate
5. customevaporated under reduced pressure