Stir a solution of 3,4-dimethoxybenzoic acid (85 mg, 0.461 mmol), EDC (91 mg, 0.461 mmol), HOBt (66 mg, 0.461 mmol), and Et3N (0.195 mL, 1.383 mmol) in DMF (7 mL) at room temperature for 30 min. To this add 7-(3-pyrrolidin-2-ylbenzoylamino)-3,4-dihydro-1H-isoquinoline-2-carboxylic acid benzyl ester HCl salt (236 mg, 0.384 mmol) as a solution in DMF and stir the reaction at room temperature for 48 h. Quench the reaction with sat. NH4Cl (100 mL) and extract with EtOAc (2×150 mL). Wash the organic layers with water (100 mL) then dry (Na2SO4) and concentrate to an oil. Purify by silica gel chromatography eluting with 10% EtOAc/hexane to 100% EtOAc. Concentrate the fractions containing product in vacuo to afford 137 mg of 7-{1-[1-(3,4-dimethoxy-benzoyl)-pyrrolidin-2-yl]-benzoylamino}-3,4-dihydro-1H-isoquinoline-2-carboxylic acid benzyl ester as a solid foam.
