A solution of DCC (11.3 g, 54.5 mmol) in DCM is added slowly to an ice cooled mixture of 4′-pentyl-bicyclohexyl-4-carboxylic acid (15.0 g, 53.5 mmol), dimethylaminopyridine (1.1 g) and 3-bromopropan-1-ol (7.5 g, 54.0 mmol) and DCM (100 ml). After addition is complete, the mixture is stirred at 25° C. overnight. Oxalic acid is added to mop up excess DCC, the mixture is filtered and then evaporated to dryness to afford 4′-pentyl-bicyclohexyl-4-carboxylic acid 3-bromo-propyl ester as a white solid which gave correct mass ion by GCMS (M+401). 1H NMR gave expected signals. The product is used without further purification in the preparation of preferred example 2.
