Total Synthesis of (+)-Clavilactone A and (-)-Clavilactone B by Ring-Opening/Ring-Closing Metathesis

The enantioselective total synthesis of natural enantiomers of clavilactones A and B has been achieved. A key feature of the synthesis is the use of a ring-opening/ring-closing metathesis, which allows the one-pot transformation of a strained cyclobutenecarboxylate into a gamma-butenolide.