反应详情

Activated manganese dioxide (69 g) was added to a solution of benzyl 9-methoxy-1,3-dioxo-1,2,3,3a,4,5,6,10c-octahydropyrrolo[3,4-c]carbazole-4-carboxylate (13.76 g, 0.034 mol), prepared as in example 2, in p-dioxane (300 mL) and the mixture was refluxed with vigorous stirring for 0.5–2 h. The mixture was filtered while hot through a plug of Celite, which was washed exhaustively with a MeOH/p-dioxane (1:1) mixture until the washings were colorless. The combined washings and filtrate were concentrated to dryness and the residue triturated several times with diethyl ether to give benzyl 9-methoxy-1,3-dioxo-1,2,3,6-tetrahydropyrrolo[3,4-c]carbazole-4-carboxylate (4) as a yellow/orange powder (12.47 g, 91.5%), mp 245° C. A small sample was recrystallised from EtOAc to give benzyl 9-methoxy-1,3-dioxo-1,2,3,6-tetrahydropyrrolo[3,4-c]carbazole-4-carboxylate as orange cubes; mp 289–292° C. 1H NMR δ (CD3)2SO] 12.11 (br s, 1H), 11.27 (br s, 1H), 8.45 (d, J=2.6 Hz, 1H), 7.98 (s, 1H), 7.59 (d, J=8.9 Hz, 1H), 7.55–7.51 (m, 2H), 7.44–7.34 (m, 3H), 7.27 (dd, J=8.9, 2.6 Hz, 1H), 5.41 (s, 2H), 3.88 (s, 3H). Found: C, 68,99; H, 4.09; 6.91. C23H16N2O5 requires C, 69.00; H, 4.03; N, 6.99.

1. temperaturethe mixture was refluxed
2. filtrationThe mixture was filtered while hot through a plug of Celite, which
3. washwas washed exhaustively with a MeOH/p-dioxane (1:1) mixture until the washings
4. concentrationThe combined washings and filtrate were concentrated to dryness
5. customthe residue triturated several times with diethyl ether