Development of the Catalytic Asymmetric Tandem Reactions

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We have found a nickel-catalyzed asymmetric multiple-component coupling of enones, alkynes, dimethylzinc, and chlorotrimethylsilane. Interestingly, catalytic systems involving simple monodentate chiral oxazolines, which have been previously used as valuable chiral auxiliaries, were very effective in giving optically active coupling products. In contrast some optically active organophosphorus ligands and bidentate oxazolines, which have been extensively used as ligands for transition metals in asymmetric catalysis, did not give enantioselection. Moreover, we have found an asymmetric cyclotrimerization of enones and alkynes in the presence of a catalytic system of nickel and aluminum. The chiral monooxazoline ligands were also effective in the reaction.