Preferred embodiments of the invention include mixtures of compounds of formulas IVa and IVb, including racemic mixtures. In another preferred embodiment, the compounds of formula IVa and IVb are the separate enantiomers of (±)-cis-3-(5,6-dihydro-4H-pyrrolo[3,2,1-ij]quinolin-1yl)-4(1H-indol-3-yl)pyrrolidine-2,5-dione. In this embodiment the preparation of (±)-cis-3-(5,6-dihydro-4H-pyrrolo[3,2,1-ij]quinolin-1yl)-4(1H-indol-3-yl)pyrrolidine-2,5-dione is prepared as a mixture beginning with the starting materials 1,2,3,4-tetrahydroquinoline and indole-3-acetamide. The 1,2,3,4-tetrahydroquinoline is converted into 5,6-dihydro-4H-pyrrolo[3,2,1-ij]quinolin-1-yl)oxoacetic acid methyl ester as described in Example 1, steps 1-5. The 5,6-dihydro-4H-pyrrolo[3,2,1-ij]quinolin-1-yl)oxoacetic acid methyl ester is reacted with indole-3-acetamide as described in Example 1, step 6, to yield 3-(5,6-dihydro-4H-pyrrolo[3,2,1-ij]quinolin-1yl)-4(1H-indol-3-yl)pyrrole-2,5-dione. The mixture of (±)-cis-3-(5,6-dihydro-4H-pyrrolo[3,2,1-ij]quinolin-1yl)-4(1H-indol-3-yl)pyrrolidine-2,5-dione is then prepared by catalytic hydrogenation as described in Example 2 using Procedure B.
