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1998.9 - 2002.6 Southwest China Normal University, B. S.
2002.9 - 2007.12 Nankai University, SKLEOC, Ph. D.
2008.1 - Now Rutgers, the State University of New Jersey
Address: 192A, Cedar Lane, Highland Park, New Jersey 08904
Chiral amine is an essential structural unit in natural products and a key function group in many biologically active molecules. The catalytic asymmetric hydrogenation of functionalized enamines such as a- and b-N-acylamino acrylates, and enamides is one of the most efficient methods to form chiral primary and secondary amine derivatives. However, very few enantioselective methods have been reported for the synthesis of chiral tertiary amines. In this dissertation, we focus on the asymmetric hydrogenation of unprotected enamines using monodentate phosphorus ligands containing 1,1'-spirobiindane backbone.
The synthesis of phosphonite ligands containing a 1,1a-spirobiindane scaffold and their application in Rh-catalyzed asymmetric hydrogenation of unprotected acyclic N,N-dialkylenamines. The spiro phosphonite ligand was found to be a good ligand for this reaction. Using I2 and acetic acid as additives, the reaction can proceed under mild conditions in 100% conversion, providing the corresponding tertiary amines in high yields with excellent enantioselectivities (up to 99.9% ee). This is the best result reported in literature.
For the first time, the highly enantioselective Ir-catalyzed asymmetric hydrogenation of unprotected cyclic enamines was realized by using Ir/(S,R,R)-SIPHOS-PE complex as catalyst and I2 as additive, affording the cyclic tertiary amines in excellent enantioselectivities (up to 96% ee).
Furthermore, the Ir-catalyzed asymmetric hydrogenation of the unprotected acyclic enamines was also investigated. Although the most results were not better than those obtained by the Rh catalyst, the enantioselectivities of up to 98% ee have been achieved in the hydrogenation of orth-substituent substrates, which is higher than those obtained by Rh catalyst.
Keywords: unprotected enamines, spiro phosphonite, rhodium, iridium, asymmetric hydrogenation, catalysis.
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