Tandem transfer hydrogenation cascade

Scheme 3.50 Intramolecular aldol condensation/tandem transfer hydrogenation cascade.

Almost at the same time, Liu and Che published a cascade intermolecular hydroamination/asymmetric reduction sequence, which included achiral Au complex-catalyzed hydroamination of aryl amines and chiral phosphoric acid-promoted Hantzsch ester reduction to afford secondary aryl amines [70], More recently, the same group reported a tandem one-pot assembly of functionalized tetrahydroquino-lines from amino aldehyde and alkynes by combining Au and chiral phosphoric acid catalysis [71], The reaction was initiated by Au-promotedquinololine 210 generation, followed by an enantioselective HEH-incorporated transfer hydrogenation process (Scheme 9.67). 

N. Shindoh, H. Tokuyama, Y. Takemoto, K. Takasu, J. Org. Chem. 2008,73, 7451-7456. Auto-tandem catalysis in the synthesis of substituted quinolines from aldimines and electron-rich olefins cascade Povarov-hydrogen-transfer reaction. 

In 2010, Bruneau and co-workers described an unprecedented cascade N- and C(3)-dialkylation of unactivated cyclic amines with benzylic and aliphatic alcohols using a new (arene)mthenium (II) complex 7 bearing a phosphinosulfonate ligand as the catalyst (Eq. 17) [94]. In 2012, they achieved a three-component N- and C-dialkylation reaction of the easily accessible anilines, diols, and aldehydes through tandem hydrogen transfer reactions in the presence of iridium complex 8 (Eq. 18) [95]. 

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