Asymmetric Intramolecular Alkylation of Chiral Aromatic Imines via Catalytic C-H Bond Activation

Abstract

The asymmetric intramolecular alkylation of chiral aromatic aldimines, in which differentially substituted alkenes are tethered meta to the imine, was investigated. High enantioselectivities were obtained for imines prepared from aminoindane derivatives, which function as directing groups for the rhodium-catalyzed C-H bond activation. Initial demonstration of catalytic asymmetric intramolecular alkylation also was achieved by employing a sterically hindered achiral imine substrate and catalytic amounts of a chiral amine.

Key words

C-H bond activation - asymmetric catalysis - transimination - cyclization - dihydrobenzofuran

References and Notes

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9

Ti(OPh)₄ was prepared in situ by the addition of 4 equiv of phenol to 1 equiv of Ti(Oi-Pr)₄ in THF at r.t. Ti(OPh)₄ was obtained as an orange solid after removal of the solvent.