A cross metathesis approach to the synthesis of the C11–C23 fragment of (−)-16-normethyldictyostatin

The synthesis of the C11–C23 fragment 2 of (−)-16-normethyldictyostatin has been achieved by cross metathesis between two olefinic fragments 4 and 5 followed by a reduction of the double bond at C16–C17. Both the olefinic fragments are easily synthesized in a diastereoselective manner from the common precursor alcohol 7.