Water → 2,3-Dimethoxy-8,9-methylenedioxy-dibenzo[c,h]cinnoline

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Reaction Steps

6-(2-Amino-4,5-methylenedioxyphenyl)-2,3-dimethoxy-naphthalene (13, 40 mg, 0.13 mmol) in acetic acid (2 mL) and concentrated hydrochloric acid (0.3 mL) was cooled to 0° C. and diazotised with a solution of sodium nitrite (0.09 g in 1.5 mL water). The diazonium solution was allowed to rise slowly to room temperature and left overnight. Water (50 mL) was added to the red solution with some precipitate. The resulting mixture was extracted with ethyl acetate, washed with diluted sodium hydroxide solution, then with water, dried (anhydrous Na2SO4) and rotaevaporated to give the crude product. Chromatography on silica gel using 40:60 hexanes:ethyl acetate afforded the title compound (20 mg) in 50% yield; 1H NMR (CDCl3) d 4.09(3H, s), 4.22(3H, s), 6.24(2H, s), 7.31(1H, s), 7.80(1H s), 7.95(1H, s), 8.00(1H, d, J=9.2), 8.13(1H, d, J=8.9), 9.14(1H, s); 13C NMR d 56.5 56.9, 98.1, 102.9, 104.6, 107.5, 107.9, 117.1, 119.6, 120.6, 126.8, 128.5, 131.7, 141.9, 145.6, 150.2, 151.2, 152.1.

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