Ruthenium-catalysed cyclisation reactions of 1,11-dien-6-ynes leading to biindenes

1,2-Bis(2-allylphenyl)ethynes undergo cycloisomerisation reactions in the presence of Cp*Ru( ii ) catalysts to produce 2,2′-dimethyl-3 H ,3′ H -1,1′-biindenes. On the other hand, tandem ring-closing metathesis of 1,2-bis(2-allylphenyl)ethynes using the Hoveyda-Grubbs 2nd generation catalyst led to the formation of 2,2′-unsubstituted biindenes. Various symmetrical and unsymmetrical bicyclic dienes were prepared by these ruthenium-based cyclisation methods. 1,1′-Biindenes were prepared from 1,2-bis(2-allylphenyl)ethynes via cycloisomerisation and tandem RCM reactions, both of which are catalysed by ruthenium.