On the relationship of OSW-1 to the cephalostatins

Antineoplastic bis-steroidal (cephalostatin-type) analogues of the saponin OSW-1 were produced from a dihydroaglycone of OSW-1. The key aglycone 6H was obtained from 5α-androstan-3β-ol-17-one in 8 steps (38% yield). The SAR of the aglycones, intermediates, and hybrid analogues provide insights regarding the proposed common role of C22-oxocarbenium ions in the bioactivity of both OSW-1 and cephalostatins