cis-4-(3,5-Bis-trfluoromethyl-benzylamino)-6,7-dimethoxy-3,4-dihydro-2H-quinoline-1,2-dicarboxylic acid 2-butyl ester 1-ethyl ester (Example 4) (approximately 500 mg, 0.83 mmol) and pyridine (195 mg, 2.5 mmol) were dissolved in anhydrous dichloromethane (100 mL) and cooled to 0° C. Methyl chloroformate (195 mg, 2.1 mmol) was added slowly. The reaction was stirred at 0° C. for 1 h, then at room temperature for 18 h. The reaction mixture was then diluted with chloroform, and washed with 1N HCl. The organic layer was dried over magnesium sulfate, filtered and concentrated in vacuo. Purification by silica gel chromatography using 15% ethyl acetate/hexanes as eluent afforded the title product (400 mg). MS m/z 664.2 (M+); 1H NMR (CDCl3) δ 0.9 (t, 3H), 1.3 (t, 3H), 1.5 (m, 2H), 3.85 (s, 3H), 4.0 (t, 2H) 6.3 (s, 1H), 7.8 (s, 1H).
