A novel and practical synthesis of CAT3: a phenanthroindolizidine alkaloid with potential in treating glioblastoma

CAT3, one of the (+)-deoxytylophorinine-based phenanthroindolizidine alkaloids, is a promising therapeutic agent for the treatment of hedgehog (Hh)-driven glioblastoma and is currently being evaluated in preclinical studies. In this paper, a novel and practical synthetic route for CAT3 was firstly demonstrated with 10% overall yield in 11 steps and has been successfully validated for pilot-plant scale preparation. Investigation of the substitution at the 3-position of phenanthrene revealed that the electron-donating functionality can well preserve the S configuration. In particular, the excellent enantiomeric excess of CAT3 (≥99% ee) was achieved by introducing the strongly electron-donating tert-butyldimethylsilyl (TBS) group.