Thionyl Chloride → Ethyl 3-(4-fluorophenyl)-7-hydroxyisoxazolo[4,5-c]pyridine-6-carboxylate

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Reaction Conditions

Reaction Steps

Ethyl 4-(((2,4-dimethoxybenzyl)(2-ethoxy-2-oxoethyl)amino)methyl)-3-(4-fluorophenyl)isoxazole-5-carboxylate (8.7 g, 17.4 mmol) was dissolved in 150 mL of THF and cooled to −78° C. Potassium tert-butoxide solution (34.8 mL, 34.8 mmol, 1M in THF) was added dropwise, and the mixture was stirred for 14 hours, the cold bath allowed to evaporate spontaneously. The reaction mixture was quenched with 30 mL of 1M HCl and 200 mL of saturated ammonium chloride solution. The product was extracted with EtOAc and the organic layer was dried over MgSO4 and concentrated to give 7.54 g of crude oil. The crude intermediate was dissolved in 100 mL of CH2Cl2. Thionyl chloride (1.8 mL, 24.9 mmol) was added and within minutes a precipitate began to form. The reaction mixture was stirred for another hour and the mixture was filtered through a medium porosity funnel. The solid was rinsed twice with cold CH2Cl2 and dried under vacuum to give 3.63 g of the title compound. MS: (+) m/z 303.37 (M+1).

Provenance & Evidence