title: PyBidine-Cu(OTf)2 -catalyzed asymmetric [3+2] cycloaddition with imino esters: harmony of Cu-Lewis acid and imidazolidine-NH hydrogen bonding in concerto catalysis.
abstract: A bis(imidazolidine)pyridine (PyBidine)-Cu(OTf)2 complex catalyzing the endo-selective [3+2] cycloaddition of nitroalkenes with imino esters was applied to the reaction of methyleneindolinones with imino esters to afford spiro[pyrrolidin-3,3'-oxindole]s in up to 98 % ee. X-ray crystallographic analysis of the PyBidine-Cu(OTf)2 complex and DFT calculations suggested that an intermediate Cu enolate of the imino ester reacts with nitroalkenes or methyleneindolinones, which are activated by NH-hydrogen bonding with the PyBidine-Cu(OTf)2 catalyst.
authors.affiliation: Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522 (Japan) http://synthesis.chem.chiba-u.jp/index.html. tarai@faculty.chiba-u.jp.
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Arai
authors.forename: Hiroki
authors.initials: H
authors.lastname: Ogawa
authors.forename: Atsuko
authors.initials: A
authors.lastname: Awata
authors.forename: Makoto
authors.initials: M
authors.lastname: Sato
authors.forename: Megumi
authors.initials: M
authors.lastname: Watabe
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamanaka
mesh_terms: D000475:Alkenes / Q000737:chemistry; D002384:Catalysis; D056831:Coordination Complexes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D061565:Cycloaddition Reaction; D004952:Esters; D006860:Hydrogen Bonding; D048289:Imidazolidines / Q000737:chemistry*; D007097:Imines / Q000737:chemistry; D058116:Lewis Acids / Q000737:chemistry*; D008698:Mesylates / Q000737:chemistry*; D008968:Molecular Conformation; D011725:Pyridines / Q000737:chemistry
chemical_list: D000475:Alkenes; D056831:Coordination Complexes; D004952:Esters; D048289:Imidazolidines; D007097:Imines; D058116:Lewis Acids; D008698:Mesylates; D011725:Pyridines; C012077:trifluoromethanesulfonic acid; C023666:pyridine
keywords: asymmetric catalysis; asymmetric synthesis; cycloaddition; heterocycles; indoles