Structural comparisons of isomeric series of 7-aryl-benzo[h]pyrazolo[3,4-b]quinolines and 11-aryl-benzo[f]pyrazolo[3,4-b]quinolines.

The structures of three new 7-aryl-benzo[h]pyrazolo[3,4-b]quinolines, 8-methyl-7-(4-chlorophenyl)-10-phenyl-6,10-dihydro-5H-benzo[h]pyrazolo[3,4-b]quinoline, C(27)H(20)ClN(3), 8-methyl-7-(3-pyridinyl)-10-phenyl-6,10-dihydro-5H-benzo[b]pyrazolo[3,4-b]quinoline, C(26)H(20)N(4), and 8-methyl-7-(4-pyridinyl)-10-phenyl-10H-benzo[h]pyrazolo[3,4-b]quinoline, C(26)H(18)N(4), which is an unexpected oxidation product isolated from the attempted synthesis of 8-methyl-7-(4-pyridinyl)-10-phenyl-6,10-dihydro-5H-benzo[h]pyrazolo[3,4-b]quinoline, and those of three new 11-aryl-benzo[f]pyrazolo[3,4-b]quinolines, 11-(4-methylphenyl)-10-methyl-8-phenyl-6,8-dihydro-5H-benzo[f]pyrazolo[3,4-b]quinoline, C(28)H(23)N(3) (P\bar 1, Z' = 2), 11-(4-methoxyphenyl)-10-methyl-8-phenyl-6,8-dihydro-5H-benzo[f]pyrazolo[3,4-b]quinoline, C(28)H(23)N(3)O (P2(1)/c, Z' = 4), and 11-(3,4,5-trimethoxyphenyl)-10-methyl-8-phenyl-6,8-dihydro-5H-benzo[f]pyrazolo[3,4-b]quinoline, C(30)H(27)N(3)O(3), are reported. The crystal structures are compared with those of a number of analogues reported in the recent literature; in particular, structural comparisons are drawn within each series as the substituted pendent aryl group is varied, and between several pairs of strictly isomeric 7-aryl-benzo[h]pyrazolo[3,4-b]quinolines and 11-aryl-benzo[f]pyrazolo[3,4-b]quinolines containing the same aryl substituents within each pair. Intermolecular interactions of the C-H...pi type are found in the crystal structures of both series, but pi...pi stacking interactions are found only in the 7-aryl-benzo[h]pyrazolo[3,4-b]quinoline series.