An efficient synthesis of the C-23 deoxy, 17 alpha-hydroxy South 1 hemisphere and its cephalostatin 1 analog.

[reaction: see text] Methods for functionalization of the D ring of diene 1 were investigated. This study led to efficient syntheses of 3 and the subsequent 23'-deoxy,17'alpha-hydroxy cephalostatin 1 analog (4). The bioactivity data of 2 and 4 are in the low nanomolar range for a 10-cell-line minipanel.