title: Well-defined binuclear chiral spiro copper catalysts for enantioselective N-H insertion.
abstract: An asymmetric N-H insertion of α-diazoesters with anilines catalyzed by well-defined copper complexes of chiral spiro bisoxazoline ligands was studied in detail. The copper-catalyzed asymmetric N-H insertion of a wide range of α-alkyl-α-diazoacetates with anilines was accomplished with excellent enantioselectivity (up to 98% ee) and provided an efficient method for the preparation of optically active α-amino acid derivatives. A correlation study of the electronic properties of the substrates with the enantioselectivity of the N-H insertion reaction supports a stepwise insertion mechanism, and the significant first-order kinetic isotope effect proves that the proton transfer is most likely the rate-limiting step. A binuclear chiral spiro copper catalyst having 14-electron copper centers, a trans coordination model, a perfect C(2)-symmetric chiral pocket, and significant Cu-Cu interaction was isolated and extensively studied. The novel structure of the binuclear chiral spiro copper catalyst leads to unique reactivity as well as enantioselectivity in the N-H insertion reaction.
authors: State Key Laboratory and Institute of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, China.
authors: Shou-Fei
authors: SF
authors: Zhu
authors: Bin
authors: B
authors: Xu
authors: Guo-Peng
authors: GP
authors: Wang
authors: Qi-Lin
authors: QL
authors: Zhou
mesh_terms: D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009584:Nitrogen / Q000737:chemistry*; D013141:Spiro Compounds / Q000737:chemistry*; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: D013141:Spiro Compounds; D003300:Copper; D006859:Hydrogen; D009584:Nitrogen