(4-Oxo-cyclohexyl)-acetic acid methyl ester

Synthesis

The general procedure for the synthesis of methyl 2-(4-oxocyclohexyl)acetate from methyl 2-(1,4-dioxaspiro[4.5]decan-8-yl)acetate was as follows: methyl 2-(4-(1,3-dioxaspiro[4.5]cyclohexyl)acetate (51.1 g, 238 mmol, 1.0 equiv) was dissolved in tetrahydrofuran (2 L). The solution was cooled to 0 °C and 2N hydrochloric acid (1.4 L, 2.8 mol, 12.0 eq.) was added slowly and dropwise over 2.5 h. The reaction temperature was kept at 0 °C. The reaction mixture was stirred overnight and allowed to warm up naturally to room temperature. Subsequently, water (1 L) and ethyl acetate (1 L) were added to separate the organic and aqueous layers. The aqueous layer was extracted with ethyl acetate (1 L). The organic layers were combined, washed with saturated saline (1 L) and dried with anhydrous sodium sulfate. After evaporation of the solvent under reduced pressure, the product was purified by column chromatography (silica gel: ethyl acetate/heptane=1/4). Methyl 2-(4-oxocyclohexyl)acetate 21.9 g was obtained in 54% yield as a clear oil.1H NMR (CDCl3, 300 MHz) δ 1.50 (m, 2H), 2.16 (m, 2H), 2.36 (d, 2H), 2.38 (m, 1H), 2.39 (m, 4H), 3.71 (s, 3H).

References

[1] Patent: EP2256105, 2010, A1. Location in patent: Page/Page column 25; 26
[2] Patent: EP2471777, 2012, A1. Location in patent: Page/Page column 10
[3] Patent: US2009/36425, 2009, A1. Location in patent: Page/Page column 18