Diastereoselective Imine-Bond Formation through Complementary Double-Helix Formation

• Published in: Journal of the American Chemical Society Vol. 134; no. 17; pp. 7250 - 7253
• Main Authors: Yamada, Hidekazu, Furusho, Yoshio, Yashima, Eiji
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 02.05.2012; Amer Chemical Soc
• Subjects: Amidines - chemical synthesis; Amidines - chemistry; Carboxylic Acids - chemical synthesis; Carboxylic Acids - chemistry; Chemistry; Chemistry, Multidisciplinary; Cyclohexylamines - chemical synthesis; Cyclohexylamines - chemistry; Dimerization; Imines - chemical synthesis; Imines - chemistry; Magnetic Resonance Spectroscopy; Physical Sciences; Science & Technology; Stereoisomerism; ORGANIC-SYNTHESIS; POLYMERS; SELF-REPLICATING PEPTIDE; RNA; DNA-TEMPLATED POLYMERIZATION; NUCLEIC-ACID ALDEHYDES; ARTIFICIAL DOUBLE HELICES; CHAIN-LENGTH; DIRECTED SYNTHESIS; MOLECULES
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja301430h

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.