Total synthesis of (-)-callystatin A.

[reaction: see text] The enantioselective synthesis of callystatin A is described. The pivotal step in the synthesis is the stereoselective aldol reaction that generates the beta-hydroxy ketone moiety. Utilizing the allylic strain within the ethyl ketone precursor, we were able to generate the all-syn configuration of callystatin A. For the construction of the two diene moieties, both a Heck coupling and a Wittig reaction were employed.