Au l Br0nsted Acid System

SCHEME 2.97 Synthesis of chiral tetrahydroquinolines under Au/chiral phosphoric acid-catalyzed hydroamination/transfer hydrogenation cascade. 

SCHEME 2.98 Gold(I)/chiral Brpnsted acid-catalyzed tandem process for the construction 

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Au(l)/Br0nsted Acid System Han et al. developed an unprecedented protocol to synthesize tetrahydroquinolines 332 directly from 2-(2-propynyl)aniline derivatives 365 in one pot under relay catalysis of an achiral Au complex 368 and a chiral phosphoric acid 5j [131]. The Au -catalyzed intramolecular hydroamination of 2-(2-propynyl)aniline provided the 1,4-dihydroquinolines 366, followed by isomerization into imine-like 3,4-dihydroquinoliniums 367 with 5j. This active intermediate then underwent asymmetric transfer hydrogenation with Hantzsch ester to produce enantioenriched tetrahydroquinoUne products (Scheme 2.97). 

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