Formaldehyde → 3-(5-Phenyl-4-(trifluoromethyl)isoxazol-3-yl)prop-2-yn-1-ol

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To a solution of 3-(2,2-dibromovinyl)-5-phenyl-4-(trifluoromethyl)isoxazole (Preparation 62A, 0.496 g, 1.19 mmol) in THF (6.0 mL) at −78° C. was slowly added a 2.5 M solution of butyl lithium in hexane (1.05 mL, 2.61 mmol). The reaction mixture was stirred at −78° C. for 25 min. and then warmed to room temperature gently with a heat gun. Once at room temperature, paraformaldehyde (0.713 g, 23.74 mmol) was added, and the reaction mixture was stirred for 5 min. The mixture was diluted with ether, washed with water (2×), and washed with brine. The combined aqueous layers were extracted with ether, and the combined organics layers were dried over anhydrous sodium sulfate and concentrated. The residue was purified by flash silica gel chromatography using a mixture of ethyl acetate in hexane (1%-5%-20%) to give 3-(5-phenyl-4-(trifluoromethyl)isoxazol-3-yl)prop-2-yn-1-ol (0.199 g, 0.745 mmol, 63% yield) as a yellowish-orange solid. The product had an HPLC ret. time=2.39 min.−Column: Chromolith SpeedROD 4.6×50 mm (4 min.); Solvent A=10% MeOH, 90% H2O, 0.1% TFA; Solvent B=90% MeOH, 10% H2O, 0.1% TFA. LC/MS M+1=268.17.

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