The total synthesis of a bis-cyclopropane analog of the antimitotic natural product (-)-disorazole C(1) was accomplished in 23 steps and 1.1% overall yield. A vinyl cyclopropane cross-metathesis reaction generated a key (E)-alkene segment of the target molecule. IC(50) determinations of (-)-CP(2)-disorazole C(1) in human colon cancer cell lines indicated low nanomolar cytotoxic properties. Accordingly, this synthetic bioisostere represents the first biologically active disorazole analog not containing a conjugated diene or polyene substructure element.
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