Potent and Readily Accessible Bistramide A Analogues through Diverted Total Synthesis

A diverted total synthesis effort is described that is designed to prepare potent cytotoxins based on the actin-binding natural product bistramide A. The major focus of this study is the preparation of analogues that contain oxygenation at the C29 position, which is necessary for a key reaction in the sequence but is not present in the natural product. This process showed that C29 ketone analogues are accessed more readily and show similar potency compared to the natural product. The ability to incorporate C29 oxygenation and to replace a secondary alcohol by a primary alcohol allowed for the development of a more convergent approach that provides a potent analogue in just eight steps in its longest linear sequence.