Intramolecular [2+2+2] Cycloaddition Reactions of Yne-ene-yne and Yne-yne-ene Enediynes Catalysed by RhI: Experimental and Theoretical Mechanistic Studies
yields of the cycloadducts. Enediynes 1 and 2 gave standard [2+2+2] cycloaddition reactions whereas enediynes 3 and 4 suffered β‐hydride elimination followed by reductive elimination of the Wilkinson catalyst to give cycloadducts, which are isomers of those that would be obtained by standard [2+2+2] cycloaddition reactions. The different reactivities of these two types of enediyne have been rationalised