A solution of the bromide (58) (50 mg, 0.103 mmol) prepared as described in example 172 and sodium methoxide (35.2 mg, 0.65 mmol) in methanol (0.5 mL) and p-dioxane (8 mL) was refluxed for 3 h. The solution was acidified with 2N HCl, extracted with ethyl acetate and the organic layer was dried, the drying agent was removed and the solution was concentrated to dryness and chromatographed on silica. Elution with ethyl acetate gave the anhydride, 4-(2-chlorophenyl)-9-hydroxy-6-(3-methoxypropyl)-1H-furo[3,4-c]carbazole-1,3(6H)-dione as an orange powder. 1H NMR δ [(CD3)2SO] 9.57 (br, 1H), 8.24 (d, J=2.3 Hz, 1H), 8.00 (s, 1H), 7.66–7.61 (m, 2H), 7.58–7.48 (m, 3H), 7.22 (dd, J=9.0, 2.3 Hz, 1H), 4.56 (t, J=6.7 Hz, 2H), 3.22 (t, J=6.0 Hz, 2H), 3.13 (s, 3H), 2.02 (m, 2H). The product was added to molten ammonium acetate (10 g) at 140° C. and the mixture was warmed at this temperature for 3 h. Water was added and the resultant precipitate was filtered off, adsorbed onto silica from a THF solution, and chromatographed. Elution with ethyl acetate/petroleum ether (1:1) gave (132) (32 mg, 71%) an orange powder, mp 260–262° C. 1H NMR δ [(CD3)2SO] 11.07 (br s, 1H), 9.42 (br s, 1H), 8.39 (d, J=2.4 Hz, 1H), 7.69 (s, 1H), 7.60–7.44 (m, 5H), 7.15 (dd, J=8.8, 2.4 Hz, 1H), 4.49 (t, J=6.6 Hz, 2H), 3.22 (t, J=6.0 Hz, 2H), 3.13 (s, 3H), 1.99 (m, 2H). FABMS found [M+H]+: 437.1088, 435.1090. C24H20ClN2O4 requires 437.1082, 435.1112.
