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Helical Folding of Hydroxy‐Substituted N‐Hetero‐ ortho ‐phenylenes Directed by Intramolecular Hydrogen Bonds
Author(s) -
Tokoro Yuichiro,
Ohtsuka Nobuhiko,
Kusakabe Akinori,
Fukuzawa Shinichi
Publication year - 2017
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201700102
Subject(s) - chemistry , intramolecular force , random hexamer , negishi coupling , hydrogen bond , crystallography , folding (dsp implementation) , vicinal , enantiopure drug , stereochemistry , reagent , molecule , organic chemistry , enantioselective synthesis , catalysis , electrical engineering , engineering
Derivatives of the ortho ‐phenylene hexamer containing pyridine moieties and hydroxy groups were prepared through Negishi cross‐coupling reactions between bis(chloropyridyl)biphenyl and alkoxy‐substituted arylzinc reagents. X‐ray diffraction analysis revealed a closed helical folding directed by π–π stacking and hydrogen bonds. No broadening or coalescence of 1 H NMR peaks was observed between 213 and 313 K, which indicates the high stability of the helical folding in CDCl 3 solution. DFT calculations on the rotation of a single bond in the obtained compound indicated that the intramolecular hydrogen bonds led to exceptional stabilization of the closed helical folding. Right and left helices were separated by chiral column chromatography.