title: Diastereoselective imine-bond formation through complementary double-helix formation.
abstract: Optically active amidine dimer strands having a variety of chiral and achiral linkers with different stereostructures are synthesized and used as templates for diastereoselective imine-bond formations between two achiral carboxylic acid monomers bearing a terminal aldehyde group and racemic 1,2-cyclohexanediamine, resulting in a preferred-handed double helix stabilized by complementary salt bridges. The diastereoselectivity of the racemic amine is significantly affected by the chirality of the amidine residues along with the rigidity and/or chirality of the linkers in the templates. NMR and kinetic studies reveal that the present imine-bond formation involves a two-step reversible reaction. The second step involves formation of a preferred-handed complementary double helix assisted by the chiral amidine templates and determines the overall reaction rate and diastereoselectivity of the amine.
authors.affiliation: Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan.
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Yamada
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Furusho
authors.forename: Eiji
authors.initials: E
authors.lastname: Yashima
mesh_terms: D000578:Amidines / Q000138:chemical synthesis / Q000737:chemistry*; D002264:Carboxylic Acids / Q000138:chemical synthesis / Q000737:chemistry*; D003514:Cyclohexylamines / Q000138:chemical synthesis / Q000737:chemistry; D019281:Dimerization; D007097:Imines / Q000138:chemical synthesis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013237:Stereoisomerism
chemical_list: D000578:Amidines; D002264:Carboxylic Acids; D003514:Cyclohexylamines; D007097:Imines; C030435:1,2-cyclohexanediamine