3-Methyl-2-butanone → HCID 63970252, compound

Temperature

-78 °C

2-iodopyrazine (10 g, 48.55 mmol) in dry diethyl ether (100 ml) was cooled to −78° C. n-BuLi (2.5M in hexanes) (20.39 ml of 2.5 M, 50.98 mmol) was added dropwise over 10 minutes. A brown heterogeneous mixture was produced and it was stirred at −78° C. for 10 minutes, then warmed to −50° C. and stirred for an additional 60 minutes. The mixture was then re-cooled to −78° C. and 3-methylbutan-2-one (5.227 g, 6.493 ml, 60.69 mmol) was added. The mixture was stirred for 10 minutes. Further diethyl ether (10 ml) was added. The mixture was then allowed to warm to ambient. A saturated ammonium chloride aqueous solution (40 ml) and ethyl acetate (100 ml) were added and the mixture stirred for 5 minutes. The organic layer was separated and the aqueous extracted with ethyl acetate. The combined extracts were dried over magnesium sulfate, filtered and concentrated. The crude was purified on silica-gel, eluting with 40% ethyl acetate/petrol to afford the title compound as a pale yellow oil (4.74 g, 60%). 1H NMR (CDCl3) 0.75 (3H, d), 0.99-1.01 (3H, d), 1.58 (3H, s), 2.05-2.09 (1H, m), 4.10-4.40 (1H, m), 8.51-8.52 (2H, m), 8.73 (1H, s).

1. additionwas added dropwise over 10 minutes
2. customA brown heterogeneous mixture was produced
3. temperaturewarmed to −50° C.
4. stirringstirred for an additional 60 minutes
5. temperatureThe mixture was then re-cooled to −78° C.
6. stirringThe mixture was stirred for 10 minutes
7. temperatureto warm to ambient
8. stirringthe mixture stirred for 5 minutes
9. customThe organic layer was separated
10. extractionthe aqueous extracted with ethyl acetate
11. dry with materialThe combined extracts were dried over magnesium sulfate
12. filtrationfiltered
13. concentrationconcentrated
14. customThe crude was purified on silica-gel
15. washeluting with 40% ethyl acetate/petrol

ORD record

ord-473193644aa04161a329841013109de1

Source dataset

uspto-grants-2013_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08569337B2