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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
Author(s) -
Arai Takayoshi,
Ogawa Hiroki,
Awata Atsuko,
Sato Makoto,
Watabe Megumi,
Yamanaka Masahiro
Publication year - 2015
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201410782
Subject(s) - imidazolidine , chemistry , cycloaddition , catalysis , lewis acids and bases , hydrogen bond , pyridine , medicinal chemistry , oxindole , stereochemistry , polymer chemistry , organic chemistry , molecule
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.