ethyl 4-(4-chlorophenyl)-3-methyl-2,4-dioxobutanoate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The lithium enolate of ethyl 4-(4-chlorophenyl)-3-methyl-2,4-dioxobutanoate (1.5 g, 5.5 mmol) and hydroxylamine hydrochloride (0.46 g, 6.6 mmol) in absolute ethanol (30 mL) were heated to reflux for 17 hours, cooled to room temperature, then cooled to 0° C. for 3 hours. The resulting white crystals were collected and dried under vacuum to obtain ethyl 5-(4-chlorophenyl)-4-methylisoxazole-3-carboxylate (0.55 g, 0.20 mmol). to reflux for 17 hours cooled to 0° C. for 3 hours The resulting white crystals were collected dried under vacuum

Conditions: temp:-78.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A 1.0 M solution of lithium bis(trimethylsilyl)amide in tetrahydrofuran (30 mL, 30 mmol) in anhydrous diethyl ether (120 mL) under argon was cooled to −78° C. in a dry ice/acetone bath. A solution of 4-chloropropiophenone (5.0 g, 29.7 mmol) in anhydrous ether (24 mL) was added dropwise and the mixture was stirred an additional 45 minutes at −78° C. Diethyl oxalate (4.6 mL, 33.9 mmol) was added in one portion; the reaction was warmed to room temperature, and stirred overnight. The light yellow precipitate that formed was collected, washed with ether and dried under vacuum to obtain the lithium enolate of ethyl 4-(4-chlorophenyl)-3-methyl-2,4-dioxobutanoate (2.75 g, 10.0 mmol). the reaction was warmed to room temperature stirred overnight The light yellow precipitate that formed was collected washed with ether dried under vacuum