反应详情

To a Parr flask was added 10% palladium on carbon (wet degussa type) (4.47 g, 4.20 mmol) in EtOH (378 ml). Then ethyl 2-methyl-4-oxo-2-cyclohexene-1-carboxylate (23.65 ml, 140 mmol) and 5 N hydrochloric acid (1.679 ml, 8.40 mmol) were added into the reaction mixture. The atmosphere of the flask was degassed, and then filled with hydrogen (50 psi). The mixture was allowed to stir under hydrogenation conditions 30 min. The progress of the reaction was monitored by LC/MS and TLC (50% EtOAc/hexane; potassium permanganate stain), which suggested reaction completion. The mixture was filtered through a pad of celite and the filter cake was rinsed with EtOH. The mixture was concentrated in-vacuo. The crude material was purified by chromatography through an Interchim (15 micron) silica-gel column (220 g), eluting with a gradient of 0-50% EtOAc in hexane, to provide (1S,2R)-ethyl 2-methyl-4-oxocyclohexanecarboxylate (18.277 g, 99 mmol, 70.9% yield) (Racemic) as light-yellow oil. 1H NMR (400 MHz, CDCl3) δ 4.19 (dtt, 2H), 2.85 (td, J=4.25, 8.31 Hz, 1H), 2.43-2.58 (m, 4H), 2.31 (ddd, J=6.06, 8.75, 14.72 Hz, 1H), 2.01-2.21 (m, 2H), 1.29 (t, J=7.14 Hz, 3H), 0.98 (d, J=6.85 Hz, 3H); LCMS (ESI) m/z 185.0 (M+H)+.

1. customThe atmosphere of the flask was degassed
2. additionfilled with hydrogen (50 psi)
3. customreaction completion
4. filtrationThe mixture was filtered through a pad of celite
5. washthe filter cake was rinsed with EtOH
6. concentrationThe mixture was concentrated in-vacuo
7. customThe crude material was purified by chromatography through an Interchim (15 micron) silica-gel column (220 g)
8. washeluting with a gradient of 0-50% EtOAc in hexane