Diisopropylamine → 3-Ethoxy-6-(3-t-butyldimethylsilyloxypropyl)cyclohex-2-enone

Temperature

-78 °C

To a lithium diisopropylamide (LDA) solution [prepared from diisopropylamine (3.82 mL, 27 mmol) and nBuLi (7.26 mL of a 2.5M solution in hexanes, 18 mmol) in tetrahydrofuran (THF, 12 mL) at 0° C.] at −78° C. was added 3-ethoxy-2-cyclohexen-1-one (2.64 mL, 18 mmol) in THF (6 mL), dropwise, over 40 min. After stirring for an additional 30 min at −78° C., hexamethyl phosphoramide (HMPA, 3.16 mL, 18 mmol) was added followed by the dropwise addition of 3-iodo-1-tert -butyldimethylsiloxypropane (5.45 g, 18 mmol) in THF (8 mL). The resultant mixture was allowed to warm to rt, stirred for 6 h and then quenched by the addition of water (10 mL). The reaction mixture was then partitioned between dichloromethane (DCM, 100 mL) and sat. NH4Cl (40 mL). The aqueous phase was extracted with DCM (3×50 mL), the organic phases combined and washed with brine (50 mL), dried over anhydrous MgSO4 and reduced to dryness. The resultant syrup was purified by flash column chromatography (hexanes/EtOAc 8/2) to yield 2 as a pale yellow oil (2.92 g, 51.2%). Rf 0.21 (hexanes/EtOAc 8/2); 1H NMR (300 MHz, CDCl3) δ 5.26 (1H, s), 3.83 (2H, q, J=7.0 Hz), 3.59 (1H, t, J=6.5 Hz), 3.58 (H, t, J=6.5 Hz), 2.38 (2H, t, J=6.2 Hz), 2.20-1.99 (2H, m), 1.85-1.35 (5H, m), 1.31 (3H, t, J=7.0 Hz), 0.84 (s, 9H), 0.00 (s, 6H); 13C NMR (75 MHz, CDCl3) δ 201.6, 176.7, 102.3, 64.2, 63.4, 45.0, 30.5, 28.0, 26.4, 26.0 (×2), 18.4, 14.2, −5.2.

1. temperatureto warm to rt
2. stirringstirred for 6 h
3. customquenched by the addition of water (10 mL)
4. customThe reaction mixture was then partitioned between dichloromethane (DCM, 100 mL) and sat. NH4Cl (40 mL)
5. extractionThe aqueous phase was extracted with DCM (3×50 mL)
6. washwashed with brine (50 mL)
7. dry with materialdried over anhydrous MgSO4
8. customThe resultant syrup was purified by flash column chromatography (hexanes/EtOAc 8/2)

ORD record

ord-ea0940c9c5cd45cb84f4f322a50fa094

Source dataset

uspto-grants-2014_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08841132B2