2,4-Bis-benzyloxy-5-isopropenyl-benzoic acid (1.65 g, 4.4 mmol), 1-[3-(dimethylamino)propyl)]-3-ethylcarbodiimide hydrochloride (843 mg, 4.4 mmol) and 1-hydroxybenzotriazole (595 mg, 4.4 mmol) were dissolved in DMF (20 mL). After 35 minutes, the solution was added to a suspension of 4-(2,3-dihydro-1H-isoindol-5-yl)-1-methyl-piperidin-4-ol dihydrochloride (1.22 g, 4.0 mmol) in DMF (5 mL) and triethylamine (1.4 mL, 10 mmol). The mixture was stirred for 3 hours then concentrated in vacuo. The residue was taken up in ethyl acetate and washed with a mixture of water (adjusted to pH 14 with 2N sodium hydroxide solution) and brine. The aqueous phase was extracted twice further with ethyl acetate then the combined organic extracts were washed with sodium bicarbonate solution and brine, dried (MgSO4) and concentrated. The crude product was purified by flash chromatography (gradient elution with 2M methanolic ammonia/dichloromethane, 2% to 10%) to afford the title compound as a brown foam (1.62 g, 69%). 1H NMR (methanol-d4) 7.51-7.14 (14H, m), 6.85 (0.5H, s), 6.84 (0.5H, s), 5.16 (2H, s), 5.15 (2H, s), 5.10-5.08 (1H, m), 5.07-5.05 (1H, m), 4.87 (1H, s), 4.86 (1H, s), 4.61 (2H, br.s), 2.78-2.70 (2H, m), 2.57 (1H, td), 2.54 (1H, td), 2.36 (1.5H, s), 2.34 (1.5H, s), 2.16-2.05 (5H, m including 2.09 (3H, s)), 1.78-1.70 (2H, m). MS: [M+H]+ 589.
