Synthesis of and Catalytic Linear Cross-Dimerizations by an Electron-Deficient Cyclic Diene Complex of Ruthenium(0)

A ruthenium(0) complex [Ru(eta(6)-naphthalene)(eta(4)-Ph-dbcot)] (la: Ph-dbcot = 5-phenyldibenzo[a,e]cyclooctatetraene) is newly prepared in 53% yield. The IR experiment of [Ru(eta(4)-2,3-dimethylbutadiene)(eta(4)-Ph-dbcot)(CO)] (2a) shows this formal zerovalent ruthenium complex to be very electron-deficient, even though the Ph-dbcot ligand does not have any particular electron-withdrawing functional group. Complex la shows high catalytic activity toward cross-dimerization between conjugated diene with methyl acrylate with high regioselectivity.