A solution of methacrylic acid (3.5 g, 40.7 mmol) in dimethylformamide (100 ml) is added dropwise to an ice cooled slurry of sodium hydride (60% suspension in paraffin oil) (1.6 g, 40.0 mmol) in dimethylformamide (100 ml). Once addition is complete, the mixture is allowed to warm to room temperature and is stirred for 1 h, the intermediate 4′-pentyl-bicyclohexyl-4-carboxylic acid 3-bromo-propyl ester (15.0 g, 37.4 mmol) in dimethylformamide (100 ml) is added dropwise. The mixture is stirred at 50° C. overnight. The mixture is cooled to room temperature, poured into icy water, and this is extracted three times with DCM. The DCM solution is washed with brine, water and then dried over sodium sulphate. The solution is evaporated to dryness and recrystallised from industrial methylated spirits to afford a white crystalline solid.
