An approach to the core structure of leiodermatolide.

The synthesis of the 16-membered core structure of leiodermatolide 40 has been achieved in 26 linear steps starting from (R)-Roche ester. The key steps in the synthesis of 40 are a Stille cross-coupling between two main fragments 11 and 33 having roughly equal size. For the trisubstituted C4/C5 double bond a carbometalation reaction followed by a Suzuki coupling was used. A Yamaguchi macrolactonization furnished macrolactone 39.