Synthesis and in vitro cytotoxic activity of novel hexahydro-2H-pyrido[1,2-b]isoquinolines against human brain tumor cell lines

1-Hetero-substituted hexahydro-2H-pyrido[1,2-b]isoquinolines 8 – 12 were prepared with varying diastereoselectivities in 6 steps from L-phenylalanine employing a Pictet-Spengler reaction and a Lewis acidcatalyzed cyclization of imines 7 as the key steps. Compounds 6, 8a,c, 9b and 12a,b were tested in vitro against human medulloblastoma D283 Med and glioblastoma A-172 and T98G cell lines. The largest cytotoxicities were observed for 8a (LC50 = 55, 29 and 42 μmol l−1).