Enantiospecific formal total synthesis of iriomoteolide 3a.

A formal total synthesis of the marine macrolide iriomoteolide 3a is described. Salient features of the synthesis include the elaboration of a β-keto phosphonate derived from D-(-)-tartaric acid and the extension of a chiral butyrolactone derived from L-glutamic acid. Ring-closing metathesis is employed to construct the macrolactone core of the natural product.