Synthesis
Example 1: To a Parr autoclave reactor was added 150 mL of methanol followed by 25 g of methyl 4-hydroxybenzoate (nipagin methyl ester). After displacing the air in the reactor 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 reacted for 18 hours under continuous shaking. Upon completion of the reaction, the hydrogen was again 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 the catalyst. All filtrates were combined and methanol was removed by distillation under reduced pressure at about 40 °C. 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. After combining the filtrates, the solvent was removed by distillation under reduced pressure to give the crude product. The crude product was purified by a Kugelrohr short-range distillation apparatus at 80-100 °C/1 mmHg to give 25.0 g (98% yield) of the colorless oily liquid methyl 4-hydroxycyclohexanecarboxylate. 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
