A mixture of 5-[6-chloro-2-oxo-2,3-dihydro-1H-indol-3-yl]-3,4-dihydro-2H-pyridine-carboxylic acid tert-butyl ester (1.4 g, 4.00 mmol) (from Example 20a supra), 3-chlorobenzyl bromide (0.97 g, 4.67 mmol) (Aldrich), potassium iodide (0.79 g, 4.73 mmol) and potassium carbonate (1.2 g, 8.60 mmol) in acetone (30 mL) was heated at 60° C. for 12 hours in a capped pressure tube. After cooling, mixture was diluted with ethyl acetate and washed with water and brine. Aqueous layers were back washed with ethyl acetate. The organic layers were combined, dried over Na2SO4 and concentrated. The residue was purified by chromatography (ethyl acetate-dichloromethane, 1:9, V/V) to give rac-5-[6-chloro-3-(3-chloro-benzyl)-2-oxo-2,3-dihydro-1H-indol-3-yl]-3,4-dihydro-2H-pyridine-carboxylic acid tert-butyl ester as a brown solid. (Yield 1.5 g, 79%).
