Studies on the Constituents of the Seeds of Hernandia ovigera L. V. : Syntheses of Epipodophyllotoxin and Podophyllotoxin from Desoxypodophyllotoxin

Epipodophyllotoxin (EPT) and podophyllotoxin (PT) were prepared from desoxypodophyllotoxin (DPT), obtained from the seeds of Hernandia ovigera L. (Hernandiaceae) EPT was obtaind together with dehydrodesoxypodophyllotoxin (I) by a radical bromination of DPT with N-bromosuccinimide (NBS) followed by hydrolysis of the resultant 1-bromo-DPT, which was confirmed to be a mixture of 1α- and 1β-bromo compounds (7 : 3). EPT was oxidized with pyridinium chlorochromate to give podophyllotoxone (IV). The stereoselective reduction of IV to afford PT was examined with a variety of reagents, and borane-tert-butylamine complex was found to be effective.