title: Catalytic Asymmetric Iodocyclization of N-Tosyl Alkenamides using Aminoiminophenoxy Copper Carboxylate: A Concise Synthesis of Chiral 8-Oxa-6-Azabicyclo[3.2.1]octanes.
abstract: A newly developed aminoiminophenoxy copper carboxylate (L7-Cu-OAc)-catalyzed asymmetric iodocyclization of N-Tosyl alkenamides gave O-cyclized products in good yields with high enantioselectivity. From the O-cyclized products, a skeletal transformation was succeeded in the synthesis of biologically important chiral 8-oxa-6-azabicyclo[3.2.1]octanes. DFT calculations suggested that the acetoxy anion of the [L7-Cu-OAc] acts as a base to generate the anion of N-Tosyl alkenamide substrates. The exchanged acetic acid reconstructs a new hydrogen-bonding network between the catalyst and the substrates to accomplish the highly efficient asymmetric O-iodocyclization of N-Tosyl alkenamides.
authors.affiliation: Molecular Chirality Research Center, Synthetic Organic Chemistry, Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522 (Japan). tarai@faculty.chiba-u.jp.
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Arai
authors.affiliation: Molecular Chirality Research Center, Synthetic Organic Chemistry, Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522 (Japan).
authors.forename: Ohji
authors.initials: O
authors.lastname: Watanabe
authors.affiliation: Department of Chemistry, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501 (Japan).
authors.forename: Shinnosuke
authors.initials: S
authors.lastname: Yabe
authors.affiliation: Department of Chemistry, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501 (Japan).
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamanaka
mesh_terms: D000577:Amides / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D003500:Cyclization; D054879:Halogenation; D007455:Iodine / Q000737:chemistry*; D008958:Models, Molecular; D013237:Stereoisomerism; D014105:Tosyl Compounds / Q000737:chemistry*; D014326:Tropanes / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000577:Amides; D002264:Carboxylic Acids; D014105:Tosyl Compounds; D014326:Tropanes; D003300:Copper; D007455:Iodine
keywords: DFT calculations; asymmetric catalysis; copper; cyclization; halogenation