Diastereoselective imine-bond formation through complementary double-helix formation

J Am Chem Soc. 2012 May 2;134(17):7250-3. doi: 10.1021/ja301430h. Epub 2012 Apr 24.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amidines / chemical synthesis
  • Amidines / chemistry*
  • Carboxylic Acids / chemical synthesis
  • Carboxylic Acids / chemistry*
  • Cyclohexylamines / chemical synthesis
  • Cyclohexylamines / chemistry
  • Dimerization
  • Imines / chemical synthesis
  • Imines / chemistry*
  • Magnetic Resonance Spectroscopy
  • Stereoisomerism

Substances

  • Amidines
  • Carboxylic Acids
  • Cyclohexylamines
  • Imines
  • 1,2-cyclohexanediamine