Synthesis
Example 1: To a Parr high pressure reaction flask was added 150 mL of methanol followed by 25 g of methyl 4-hydroxybenzoate (nipagin methyl ester). After displacing the air in the reaction flask with nitrogen, 2.5 g of 5% rhodium/alumina catalyst was added. The reaction mixture was pressurized to 3.74 MPa under hydrogen atmosphere and the reaction was continuously shaken at room temperature for 18 hours. Upon completion of the reaction, the hydrogen was replaced with nitrogen and the reaction mixture was filtered through a diatomaceous earth pad to separate the catalyst. The diatomaceous earth pad was washed with methanol, taking care to avoid drying of the catalyst. The filtrate and washings were combined and concentrated under reduced pressure at 40 °C to remove methanol. The residue was dissolved in 200 mL of ether and 3 g of anhydrous potassium carbonate was added. The precipitated alumina and potassium carbonate were removed by diatomaceous earth filtration and washed with ether. The filtrates were combined and the solvent was removed under reduced pressure to give the crude product. The crude product was distilled by a Kugelrohr short-range distillation apparatus at 80-100 °C/1 mmHg to give 25.0 g (98% yield) of methyl 4-hydroxycyclohexanecarboxylate (cis-4-hydroxycyclohexanecarboxylic acid methyl ester). The product was characterized by 1H NMR (CDCl3, 60 MHz): δ 3.85 (s, 1H); 3.65 (s, 3H); 2.50-1.20 (m, 10H).
References
[1] Canadian Journal of Chemistry, 1982, vol. 60, p. 1996 - 2001
[2] Journal of Organic Chemistry, 1991, vol. 56, # 5, p. 1758 - 1763
[3] Bioorganic and Medicinal Chemistry, 2005, vol. 13, # 23, p. 6309 - 6323
[4] Bulletin de la Societe Chimique de France, 1970, p. 556 - 562
[5] Bulletin de la Societe Chimique de France, 1969, p. 781 - 787
