Total synthesis of (-)-ecklonialactone B.

The total synthesis of (-)-ecklonialactone B as well as the 9,10-dihydro derivative by two different strategies is reported. The catalytic asymmetric Claisen rearrangement of Gosteli-type allyl vinyl ethers delivered elaborated α-keto ester building blocks. Ring-closing metatheses, including a notable diastereotopos-differentiating variant, a B-alkyl Suzuki-Miyaura cross-coupling reaction and a regio- and diastereoselective last-step epoxidation are key contributors.