Synthesis
Example 8: General procedure for the synthesis of methyl 2-oxo-5,5-dimethylcyclohexanecarboxylate from 4,4-dimethylcyclohexanone and dimethylcarbonate
1. To a solution of 21 g of dimethyl carbonate (0.23 mol) in anhydrous THF (400 ml) at 0 °C was slowly added sodium hydride (9.6 g, 0.24 mol).
2. The resulting mixture was stirred at 0 °C for 30 min.
3. 10 g of 4,4-dimethylcyclohexanone (79 mmol) solution in THF (100 ml) was added dropwise to the above mixture during 30 min.
4. The reaction mixture was heated to 60°C-80°C and kept for 3 hours.
5. After completion of the reaction, the mixture was cooled to room temperature.
6. The reaction mixture was poured into saturated NaHCO3 solution and extracted with ether.
7. The organic layer was washed sequentially with water and brine, dried over Na2SO4 and concentrated to give 25 g of methyl 5,5-dimethyl-2-oxocyclohexanecarboxylate (Intermediate b) in 84% yield.
MS (ESI) m/e (M + H+): 185.
References
[1] Journal of Organic Chemistry, 1998, vol. 63, # 8, p. 2548 - 2559
[2] Canadian Journal of Chemistry, 1988, vol. 66, p. 2345 - 2347
[3] Canadian Journal of Chemistry, 1997, vol. 75, # 6, p. 742 - 753
[4] Patent: WO2008/61208, 2008, A2. Location in patent: Page/Page column 42-43
[5] Patent: WO2009/143246, 2009, A2. Location in patent: Page/Page column 210
