Diastereoselective synthesis of octahydro-14H-benzo[g]quinolino-[2,3-a]quinolidines. Improved cytotoxic activity against human brain tumor cell lines as a result of the increased rigidity of the molecular backbone

Cis-Octahydro-14H-benzo[g]quinolino[2,3-a]quinolidines 6 were obtained in 6 steps from L-phenylalanine. The key step utilizes a diastereoselective intramolecular EtAlCl2-catalyzed hetero-Diels-Alder reaction. Compounds 6a-f were tested in vitro against human medulloblastoma D283 Med and glioblastoma A-172 and T98G cell lines and showed improved cytotoxicity compared to the corresponding, less rigid pyrido[1,2-b]isoquinolines 1.