Electrophilic Cyclization and Ring‐Closing Metathesis as Key Steps in the Synthesis of a 12‐Membered Cyclic Enediyne

For the first time, electrophilic cyclization and ring‐closing metathesis were used as key steps in the synthesis of a macrocyclic enediyne system, which allowed a 12‐membered dienediyne containing a thiophene‐fused ring to be obtained. The macrocycle synthesized represents a class of compounds that possess planar chirality and exists in the solid state as two enantiomers, whereas in solution the rate of interconversion is rapid as a result of unhindered switching of the double bond through the macrocycle.