Oliver Temme

Synthesis of Azapolycyclic Systems Based on the Indolizino[3,4‐b]quinoline Skeleton − A Diastereoselective Entry to Potential Oligodentate Artificial Receptors

A convenient diastereoselective synthetic route to the molecular tweezer bis(indolizino[3,4-b]quinolyl)methane 9 and the rigid indolizino[7′,8′:2,3]quinolino[8,7-h]indolizino[8,7-b]quinolines 14, 15 as potential receptor molecules has been developed, involving double imine condensation followed by Lewis acid catalyzed biscyclization of prolinal-derived bis(imines) 8 and 13, respectively. Whereas the use of SnCl4 leads to the formation of the planar polycycle 15, the corresponding concave product 14 is formed in the presence of EtAlCl2. Both compounds 14, 15, as well as tweezer 9 have been characterized by X-ray crystal-structure analysis. Although tris(imines) 20, 24 derived from 1,3,5-triaminobenzene (18) and tris(4-aminophenyl)amine (23) could be obtained similarly by molecular sieve-catalyzed condensation, the corresponding triscyclization could not be achieved. However, by attaching preformed indolizino[3,4-b]quinoline subunits 25 and 31 to an aromatic core, the bidentate receptors 30, 33 and the tentacle molecule 28 were accessible.

Effect of molecular sieves on the formation and acid-catalysed mono- and bis-cyclization of N-arylimines: easy entry to polycyclic ring systems by a novel cascade reaction

The synthesis of substituted octahydroacridines 14–17 and N-arylcyclohexylamines 18–20 from arylamines 5–8 is described. It was found that the isolation of the imines 10–13 and that Lewis acid catalysis could be avoided if molecular sieve beads were used instead of powder. The sequential molecular sieves-catalysed imine-formation/cyclization could be extended to a novel one-pot biscyclization of aryldiamines 29–31 with separated aromatic systems. However, the conversion of aryldiamines 36 and 38 with two amino groups on the same aromatic system into the corresponding biscyclization products 23 and 45 required a two-step procedure under harsher conditions.