Catalytic Version of Enediyne Cobalt‐Mediated Cycloaddition and Selective Access to Unusual Bicyclic Trienes

Go cyclic! The use of [Co(H)(PMe 3 ) 4 ] as a cobalt catalyst allows the previously unattainable catalytic version of the cobalt‐mediated cycloaddition of enediynes without the requirement of thermal or light activation (see scheme). The importance of a chelating group on the substrate that can selectively direct the reaction pathway toward the classical polycyclic 1,3‐cyclohexadienes or a new family of bicyclic trienes is also demonstrated.