Similar molecular constitutions but different conformations and different supramolecular assemblies in two related fused tetracyclic benzo[b]pyrimido[5,4-f]azepine derivatives

摘要

A simple and effective two-step approach to tricyclic pyrimidine-fused benzazepines has been adapted to give the tetracyclic analogues. In (RS)-8-chloro-6-methyl-1,2,6,7-tetrahydropyrimido[5′,4′:6,7]azepino[3,2,1-hi]indole, C15H14ClN3, (I), the five-membered ring adopts an envelope conformation, as does the reduced pyridine ring in (RS)-9-chloro-7-methyl-2,3,7,8-tetrahydro-1H-pyrimido[5′,4′:6,7]azepino[3,2,1-ij]quinoline, C16H16ClN3, (II). However, the seven-membered rings in (I) and (II) adopt very different conformations, with the result that the methyl substituent occupies a quasi-axial site in (I) but a quasi-equatorial site in (II). The molecules of (I) are linked by C—H...N hydrogen bonds to form C(5) chains and inversion-related pairs of chains are linked by a π–π stacking interaction. A combination of a C—H...π hydrogen bond and two C—Cl...π interactions links the molecules of (II) into complex sheets. Comparisons are made with some similar fused heterocyclic compounds.