Diethyl Oxalate → Ethyl 4-(hydroxyimino)-3-methyl-2-oxo-4-phenylbutanoate

Temperature

0 °C

Diisopropylamine (21 mL, 148 mmol) was added to 50 mL of THF and cooled with an external ice bath. Butyllithium (56 mL, 141 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-phenyl-propan-1-one oxime (10 g, 67 mmol) and THF (50 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, 336 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 150 mL of 3M 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 22 g of the title compound. MS: (+) m/z 250.48 (M+1).

1. temperaturecooled with an external ice bath
2. custombrought to room temperature
3. additionthe addition
4. stirringthe reaction mixture was stirred at 0° C. for 1 hour
5. temperaturewarmed to room temperature
6. customThe mixture was then transferred to a syringe
7. additionadded dropwise to a flask
8. additioncontaining
9. additionAfter the addition
10. stirringthe reaction mixture was stirred at room temperature for 18 hours
11. temperatureThe mixture was cooled in an ice bath
12. customquenched with 150 mL of 3M hydrochloric acid
13. customThe organic layer was separated
14. extractionthe aqueous layer was extracted with EtOAc
15. extractionextracted further with CH2Cl2
16. dry with materialdried over MgSO4
17. concentrationconcentrated
18. customThe crude oil was purified by chromatography (0-40% EtOAc/hexanes)

ORD record

ord-4f3488fb7f084db3814d3d9807c1a4f8

Source dataset

uspto-grants-2012_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08269008B2