Diels−Alder Reactions of Benzyne with Indenyl and Fluorenyl Ruthenium Complexes

The indenyl ruthenium compound (η5-C9H7)Ru(η5-C5Me5) (1) was found to react with benzyne, generated from o-trimethylsiylphenyl triflate by fluoride-induced 1,2-elimination, to afford the Diels−Alder adduct 1,2-(1,4-dihydronaphthalen-1,4-diyl)pentamethylruthenocene (2). When the bis(indenyl) ruthenium complex (η5-C9H7)2Ru (3) reacted with benzyne, the bisadduct 4 was obtained along with the monoadduct 5. Reaction of fluorenyl ruthenium compound (η5-C13H9)Ru(η5-C9H7) (6) with benzyne gave only the monoadduct 7 and a byproduct, 9,9′-diphenylfluorene (8). The crystal structures of 7 and 8 were determined by X-ray diffraction analysis.