Gold Phosphate-catalyzed Highly Enantioselective Transfer Hydrogenation And Amination/Transfer Hydrogenation Cascade Reaction

The prevalent appearance of1,2,3,4-tetrahydroquinoline as a key structural element in numerous natural alkaloids, bioactive molecules, and clinical pharmaceuticals has led to a great demand for the efficient construction of this skeleton. A great deal of effort has been devoted to the development of stereoselective methods for the manufacture of highly enantioenriched tetrahydroquinolines. Among the available enantioselective approaches, the asymmetric hydrogenation of quinolines turns out to be one of the most important methods, In this manuscript, we have developed two approaches for the construction of chiral1,2,3,4-tetrahydroquinoline. One is gold phosphate-catalyzed highly enantioselective transfer hydrogenation of quinolines. The other is a cascade reaction consist of amination and enantioselective transfer hydrogenation.We have found that chiral gold phosphate complexes are able to serve as highly efficient catalysts for asymmetric transfer hydrogenation of quinolines, wherein the stereoselectivity was controlled by chiral anion. The fundamental characteristic features the very high efficiency. Only0.01mol%of the gold phosphate with carbene ligand is sufficient to effectively afford the highly enantioselective transfer hydrogenation of quinolines with high stereoselectivity (up to98%ee). More interestingly, turning the achiral ligands exerts great impact on the catalytic activity.We have also developed a gold phosphate-catalyzed highly enantioselective tadem reaction for the onstruction of chiral1,2,3,4-tetrahydroquinoline and a series of nitrogen-containing compounds with special seven member ring.