Diethyl Oxalate → Ethyl 4-(hydroxyimino)-4-(4-methoxyphenyl)-3-methyl-2-oxobutanoate

Participants

Reaction Conditions

Reaction Steps

Diisopropylamine (22 mL, 154 mmol) was added to 60 mL of THF and cooled with an external ice bath. Butyllithium (59 mL, 147 mmol, 2.5 M in hexanes) was added and the mixture was stirred at 0° C. for 30 min, and brought to room temperature. The resulting LDA solution was added to a mixture of 1-(4-methoxyphenyl)propan-1-one oxime (12 g, 67.0 mmol) and THF (60 mL) at 0° C. Following the addition, the reaction mixture was stirred at 0° C. for 1 hour and warmed to room temperature. The mixture was then transferred to a syringe and added dropwise to a flask containing a pre-cooled mixture of diethyl oxalate (46 mL, 335 mmol) and THF (150 mL) at 0° C. After the addition was complete, the reaction mixture was stirred at room temperature for 18 hours. The mixture was cooled in an ice bath and quenched with 200 mL of 10% hydrochloric acid. The organic layer was separated and the aqueous layer was extracted with EtOAc. The aqueous layer was then neutralized with solid sodium bicarbonate and extracted further with CH2Cl2. The organic layers were combined, dried over MgSO4 and concentrated. The crude oil was purified by chromatography (0-40% EtOAc/hexanes) to give 17.7 g of the title compound. MS: (+) m/z 280 (M+1).

Provenance & Evidence