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, C27H20ClN3, 8-methyl- 7-(3-pyridinyl)-10-phenyl-6,10-dihydro-5H-benzo[b]pyrazolo[3,4-b] quinoline, C26H20N4, and 8-methyl-7-(4-pyridinyl)10-phenyl-10H-benzo[h]pyrazolo[3,4-b]quinoline, C26H18N4, 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-arylbenzo[f]pyrazolo[3,4-b]quinolines, 11-(4-methylphenyl)-10-methyl-8-phenyl-6,8-dihydro-5H-benzo[f]pyrazolo[3,4-b]quinoline, C28H23N3 (P similar to $(1) over bar $, Z' = 2), 11-(4-methoxyphenyl)-10-methyl-8-phenyl-6,8-dihydro-5H-benzo[ f] pyrazolo [3,4- b]quinoline, C28H23N3O(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,C30H27N3O3, 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 center dot center dot center dot 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.