Hydrochloric Acid → Methyl 4-acetyl-5-phenylisoxazole-3-carboxylate

Participants

Reaction Conditions

Reaction Steps

A solution of methyl 4-bromo-5-phenylisoxazole-3-carboxylate (358 mg, 1.269 mmol, prepared in a similar manner as described in step 9-B) and tributyl(1-ethoxyvinyl)tin (0.858 mL, 2.54 mmol) in dioxane (5 mL) was heated at 100° C. for 24 h. To the reaction mixture was added 1N aqueous hydrochloric acid (2.54 mL, 2.54 mmol), and the mixture was stirred at room temperature for 1 h. The reaction mixture was diluted with ethyl acetate (100 mL), washed with water (30 mL), washed with a saturated aqueous solution of sodium bicarbonate (30 mL), and washed with brine (30 mL). The mixture was concentrated to ˜5 mL, and potassium fluoride (0.059 mL, 2.54 mmol) in 2 mL of water was added, and the mixture was stirred for 10 minutes. The solid was filtered and washed with ethyl acetate, and the filtrate was washed with water (10 mL), washed with brine (10 mL), and dried over anhydrous sodium sulfate. Concentration followed by purification by silica gel chromatography with hexanes/ethyl acetate (10/1) afforded methyl 4-acetyl-5-phenylisoxazole-3-carboxylate (105 mg). The compound had an HPLC ret. time=2.69 min.−Column: YMC S5 COMBISCREEN® 4.6×50 mm; Gradient time: 4 min; Flow rate=4 ml/min; Solvent A=10% MeOH−90% Water−0.2% H3PO4; Solvent B=90% MeOH−10% water−0.2% H3PO4; Start % B=0; Final % B=100. LC-MS: M+1=246+.

Provenance & Evidence