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Absolute Control of Helical Handedness in Quinoline Oligoamides

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posted on 07.01.2011 by Amol M. Kendhale, Legiso Poniman, Zeyuan Dong, Katta Laxmi-Reddy, Brice Kauffmann, Yann Ferrand, Ivan Huc
The synthesis of quinoline-derived helically folded aromatic oligoamides functionalized by various chiral functions at their N-terminus is reported. When a (1S)-(−)-camphanyl moiety was introduced, it was found that helix handedness was completely shifted to right-handed helicity (de > 99%), in both protic and nonprotic solvents. The absolute helical sense and the de values were unambiguously characterized by using 1H NMR, circular dichroism (CD), and X-ray crystallography. The crystal structure of these compounds allowed us to propose a rationale for the efficiency of helix handedness induction based on a combination of steric factors and intramolecular hydrogen bonding.