The First Catalytic Asymmetric Allylation of Imines with the Tetraallylsilane−TBAF−MeOH System, Using the Chiral Bis-π-allylpalladium Complex

Abstract
The asymmetric allylation of imines with use of catalytic transition metals with chiral ligands should be a new frontier of the enantioselective C−C bond formation. So far allyltrimethylsilane, allyltrichlorosilane, and allyltrimethoxysilane have been commonly employed with use of either silane activators or dual silane−imine activators. However, tetraallylsilane is untouched in the allylation of aldimines. The first allylation of aldimines with the tetraallylsilane−TBAF−MeOH system with use of the bis-π-allylpalladium catalyst under catalytic, non-Lewis acid, essentially neutral and very mild reaction conditions has been achieved. The reaction is triggered by dual activation/promotion by TBAF and MeOH in which the fluoride anion activates the C−Si bond cleavage and MeOH promotes the facile protonation of intermediate palladium amide. Thus, the synthesis of chiral homoallylamines is achieved in a shorter reaction time and higher yields and enantioselectivities through an efficient, general, and reproducible allylation protocol for imines.

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