General procedure for the synthesis of trans-2-(methoxycarbonyl)cyclohexanecarboxylic acid from methanol and cis-1,2-cyclohexanedicarboxylic anhydride: cis-1,2-cyclohexanedicarboxylic anhydride (7.0 g, 45.5 mmol) was dissolved in methanol (2 mL, 49.5 mmol), and the reaction was stirred for 1 hour at 100 °C. Upon completion of the reaction, the solvent was removed by evaporation to afford a white solid product, trans-2-(methoxycarbonyl)cyclohexanecarboxylic acid (8.46 g, 45.5 mmol, 100% yield), which could be used in subsequent steps without further purification. The melting point of the product was 67-69 °C. Infrared spectra (KBr) showed characteristic absorption peaks: ν 3060, 1710, 1670 cm-1. 1H NMR (400 MHz, CDCl3) data: δ 7.54 (s, 1H), 3.68 (s, 3H), 2.89-2.81 (m, 2H), 2.09-1.96 (m, 2H), 1.83-1.72 (m, 2H), 1.61-1.36 (m, 2H), 1.83-1.72 (m, 2H). 1.61-1.36 (m, 4H).13C NMR (100 MHz, CDCl3) data: δ 179.76, 174.06, 51.71, 42.48, 42.33, 26.25, 25.95, 23.74, 23.62.High-resolution mass spectrometry (ESI) analysis: [M-H]-calculated value for C9H13O4 of 185.0792 and the measured value was 185.0790.
