A solution of cis-benzyl-(6,7-dimethoxy-2-methyl-1,2,3,4-tetrahydro-quinolin-4-yl)-carbamic acid ethyl ester (Example 66) (111 mg, 0.29 mmol) in anhydrous dichloromethane (2 mL), was treated sequentially with anhydrous pyridine (1 mL), and methyl chloroformate (38 μL, 0.49 mmol). After stirring at room temperature overnight, water (10 mL) and an aqueous 10% KOH solution (10 mL) were added, and the mixture was extracted with ethyl acetate (3×10 mL). The combined organic phases were then washed with 1N HCl (2×10 mL), and then a saturated sodium bicarbonate solution (10 mL). The organic layer was dried over sodium sulfate, filtered and concentrated in vacuo to give 112 mg crude product. Purification by silica gel chromatography using 0-50% ethyl acetate/hexanes as eluent afforded the desired final product (12.6 mg, 10%): MS m/z 443 (M+ +1), 460 (M++ 18); 1H NMR (CDCl3) δ 7.02 (C8, s, 1H), 6.42 (C5, s, 1H).
