Recent efforts in designing expeditious catalytic synthesis of tetrasubstituted olefins have in part been stimulated by growing needs for developing generally applicable methods for tamoxifen analogs (anti-breast cancer drug) as well as for photo-responsive organic materials and molecular devices.[1] A number of different catalytic methods have been developed to synthesize tetrasubstituted olefins, including: Suzuki-type Pd-catalyzed coupling reactions,[2] Ni- and Rh-catalyzed exocyclization methods,[3] Ni- and Pd-catalyzed nucleophilic coupling reactions of alkynes[4] and of alkyne-to-arylboronic acids,[5] Ti-catalyzed tandem alkyne-epoxide-ethyl acetate coupling,[6] and the ring-closing olefin metathesis by using Grubbs catalyst.[7] Though catalytic conjugate addition of alkenes has been recognized as a potentially powerful synthetic methodology in forming tetrasubstituted olefins, generally applicable conjugate addition of simple olefins to α,β-unsaturated carbonyl compounds has been hampered by lack of reactivity of the olefin substrates and due to the formation of homocoupling and other byproducts. Chelate-assisted C–H insertion[8] and cross coupling methods[9] are among the most notable advances in catalytic coupling reaction of enones with simple alkenes. Ni-catalyzed conjugate addition and allylic substitution reactions of simple alkenes have also been reported recently.[10] We recently discovered that the cationic complex [(C6H6)(CO)(PCy3)RuH]+BF4− (1) is a highly effective catalyst precursor for the coupling reactions of arylketones and alkenes involving C–H activation.[11] Herein we report a novel catalytic synthesis of tetrasubstituted olefins from the intermolecular conjugate addition reaction of simple olefins to α,β-unsaturated carbonyl compounds.