Enantioselective semisynthesis of novel cephalotaxine esters with potent antineoplastic activities against leukemia

Cephalotaxine-type alkaloids (CTAs), represented by homoharringtonine (HHT, 1), display potent efficacy against different types of leukemia cells. In this study, a method for hydrogenation of β-substituted itaconic acid monoesters with chiral Ru[DTBM-SegPhos](OAc)2 was developed. This metal-catalyzed asymmetric hydrogenation enabled the convenient semisynthesis of novel cephalotaxine derivatives with chiral 2'-substituted-succinic acid 4-mono-methyl esters as side chains. The preliminary structure-activity relationship (SAR) of the compounds' antineoplastic activities was studied. Eventually, we discovered compound 10b with potent antineoplastic activities against leukemia and broadly anticancer activities against a panel of cancer cells. Our study provided a highly enantioselective process enabling the semisynthesis of cephalotaxine derivatives, which are interesting for further study on a scientific basis.