(4R)-2-(N,N-diethylamino)methyl-4-(tert-butyldimethylsiloxy)cyclopent-2-en-1-one → Cyclopentanone, 3-[[(1,1-dimethylethyl)dimethylsilyl]oxy]-

Temperature

-45 °C

Lithium wire (1% Na) (68 mg, 9.7 mg-atom) was added in 0.3-cm pieces to a stirred, cooled (0° C. internal) solution of 4,4′-di-t-butylbiphenyl (2.66 g, 10.0 mmol) and 5 mg of 2,2′-bipyridyl in 20 mL of dry tetrahydrofuran (THF) under argon. The mixture was titrated to a red endpoint with n-BuLi (2.5 M in hexane, 0.12 mL) and stirred for 15 hours to form a deep blue-green solution of lithium 4,4′-di-t-butylbiphenyl. The solution was cooled to −45° C. (internal), and a solution of (R)-1-(3-chloro-1-cyclohexyl)propyl(1-ethoxyethyl)ether (1.12 g, 4.5 mmol) in 9.0 mL of dry hexane was added dropwise. After 5 minutes, a solution of 0.25 M lithium (2-thienyl)cyanocuprate in THF (20 mL) was added dropwise. After 10 minutes, a solution of (R)-2-((diethylamino)methyl)-4-(t-butyldimethylsiloxy)-2-cyclopentenone (1.12 g, 3.77 mmol) in 20 mL of dry THF was added dropwise. The solution was allowed to warm to −20° C. and was quenched into a rapidly stirred mixture of diethyl ether and saturated aqueous NH4Cl. After four hours, the layers were separated and the aqueous solution was extracted with ethyl acetate. The combined organic solutions were dried (MgSO4), filtered and concentrated and the crude product was purified by chromatography on silica to give 0.95 g (57.5%) of (3R,4R)-2-methylene-3-[(3′R)-3′-(1-ethoxy)ethoxy)-3′-cyclohexyl-1′-propyl]-4-(t-butyldimethylsiloxy)cyclopentan-1-one. NMR (CDCl3) δ0.06 (s, 3H), 0.08 (s, 3H), 0.87 (s, 9H), 0.8-1.9 (m, 15H), 1.17 and 1.20 (2 overlapping t, J=7, 3H), 1.29 and 1.30 (2 overlapping d, J=5.3, 3H), 2.30 (A of ABX, Jab=18.0, Jax=4.6, 1H), 2.62 (B of ABX, Jab=17.8, Jbx=5.8, 1H), 2.65 (br s, 1H), 3.30 (br q, J=4, 1H), 3.55 (m, J=6, 2H), 4.12 (pent, J=5.2, 1H), 4.68 (2 overlapping q, J=5.2, 1H), 5.29, 5.32 (both s, 2:3 ratio, total 1H), 6.08 (s, 1H).

1. waitAfter 10 minutes
2. temperatureto warm to −20° C.
3. customwas quenched into a rapidly stirred mixture of diethyl ether and saturated aqueous NH4Cl
4. waitAfter four hours
5. customthe layers were separated
6. extractionthe aqueous solution was extracted with ethyl acetate
7. dry with materialThe combined organic solutions were dried (MgSO4)
8. filtrationfiltered
9. concentrationconcentrated
10. customthe crude product was purified by chromatography on silica

ORD record

ord-b95e5b2b66904fb8b3493b111d3f66f3

Source dataset

uspto-grants-2002_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06388128B1