Water → 9-Hydroxy-5-methoxy-6,7-dihydro-pyrrolo[3,4-g]quinolin-8-one

Beteiligte Stoffe

Reaktionsschritte

9-Benzhydryloxy-7-(2,4-dimethoxy-benzyl)-5-methoxy-pyrrolo [3,4-g]quinoline-6,8-dione 302 (500 mg, 0.89 mmol) was dissolved in tetrahydrofuran (6.0 ml), water (1.2 ml), and isopropanol (2.4 ml) and cooled to 0° C. Lithium borohydride (LiBH4, 96.9 mg, 4.45 mmol) was then added and the reaction mixture was removed from the ice bath and stirred at room temperature for 2 hours. After quenching with acetic acid (0.5 ml), the reaction mixture was diluted with ethyl acetate, washed with twice with water, once with brine, and concentrated in vacuo. The resulting residue was dissolved in dichloromethane (9.2 ml) and triethylsilane (1.8 ml), and cooled to 0° C. After adding trifluoroacetic acid (3.6 ml), the reaction mixture was warmed to room temperature and stirred at room temperature for 1 hour. The mixture was concentrated in vacuo and the resulting residue was redissolved in trifluoroacetic acid (10 ml) and triethylsilane (2 ml). It was then warmed to 75° C. and stirred at 75° C. for 2 hours. The reaction mixture was concentrated in vacuo and azeotroped three times with a (1:1) toluene/tetrahydrofuran solution. The resulting residue was triturated three times with a (3:1) hexane/ether mixture. The remaining solid in the filter funnel and reaction flask was dissolved in methanol, combined, and concentrated in vacuo to afford 9-hydroxy-5-methoxy-6,7-dihydro-pyrrolo[3,4-g]quinolin-8-one 303 (240 mg, 113%). 1H NMR (d-DMSO) δ 8.84 (dd, 1H), 8.58 (broad, 1H), 8.50 (dd, 1H), 7.60 (m, 1H), 4.60 (s, 2H), 3.94 (s, 3H). MS: 231.1 (M+1).

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