metabolites. The structures of eight of these metabolites have been now confirmed by synthesis and their biological properties have been reported. Eaton’s reagent was utilized as a convenient condensing agent, allowing, among others, a simple multigram scale preparation of phenstatin. Synthesized metabolites and related compounds were evaluated for their antiproliferative activity in the NCI-60 cancer cell
against cellular proliferation and tubulin polymerization. In particular, monomethoxylated derivatives of phenstatin and isoCA-4 exhibit similar activities to those of parent phenstatin. Attempts of the Wittigreaction on 2- (or 4-) methoxy-4′-nitrobenzophenones in the same conditions do not lead to the expected isocombretastatins but to methyleneketones with the exclusion of triphenylphosphine. A mechanism