title: Synthesis of Highly Functionalized Chiral Benzopyrano[3,4-c]pyrrolidines Bearing Five Contiguous Stereogenic Centers.
abstract: A chiral bis(imidazolidine)pyridine-Cu complex smoothly catalyzed the asymmetric [3 + 2] cycloaddition reaction of α,β-unsaturated ester-containing nitroalkenes with imino esters to give endo-pyrrolidine products in a highly enantioselective manner while maintaining the α,β-unsaturated ester functionality. Subsequent intramolecular diastereoselective cyclizations of the obtained pyrrolidine products were accomplished by treatment with KF/Al2O3 in toluene/EtOH (4:1) to give highly functionalized benzopyrano[3,4-c]pyrrolidines bearing five contiguous stereogenic centers.
authors.affiliation: Molecular Chirality Research Center, and Department of Chemistry, Graduate School of Science, Chiba University , Inage 263-8522, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Sato
authors.affiliation: Molecular Chirality Research Center, and Department of Chemistry, Graduate School of Science, Chiba University , Inage 263-8522, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Miyazaki
authors.affiliation: Molecular Chirality Research Center, and Department of Chemistry, Graduate School of Science, Chiba University , Inage 263-8522, Japan.
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Arai