Tetrasubstituted olefins through the stereoselective catalytic intermolecular conjugate addition of simple alkenes to α,β-unsaturated carbonyl compounds.

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. A number of different catalytic methods have been developed to synthesize tetrasubstituted olefins, including: Suzuki-type Pd-catalyzed coupling reactions, Ni- and Rh-catalyzed exocyclization methods, Ni- and Pd-catalyzed nucleophilic coupling reactions of alkynes and of alkyne-to-arylboronic acids, Ti-catalyzed tandem alkyne-epoxide-ethyl acetate coupling, and the ring-closing olefin metathesis by using Grubbs catalyst. 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 and cross coupling methods 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. We recently discovered that the cationic complex [(CH)(CO)(PCy)RuH]BF () is a highly effective catalyst precursor for the coupling reactions of arylketones and alkenes involving C–H activation. 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.