Group-selective ring-closing enyne metathesis.

The ring-closing metathesis (RCM) of dienynes represents a powerful methodology for the construction of mono- and bicyclic systems containing 1,3-diene functionality. Despite its synthetic potential, the utility of dienyne RCM is significantly reduced due to poor group selectivity. To circumvent this shortcoming, several strategies utilizing steric hindrance, electronic variation, relay metathesis and ring-closure kinetics have been implemented to exert control over the reaction pathways. This article highlights a variety of methods to achieve group-selective enyne RCM of dienynes.