title: Probing persistent intramolecular C-H...X (X = O, S, Br, Cl, and F) bonding in solution using benzyl Meldrum's acid derivatives.
abstract: Persistent intramolecular interactions between acidic C-H hydrogens and a variety of acceptors (X) (X = O, S, Br, Cl, and F) in solution were probed by (1)H NMR experiments, using 5-benzyl Meldrum's acid derivatives. To bring about formation of intramolecular C-H...X bonding, ortho-substituted benzyl Meldrum's acids were designed, for which hydrogen bonding occurred through a six-membered ring. Introduction of substituents on the aromatic moiety and in the tether allowed variation of electronic and steric factors. The superior acidity of Meldrum's acids impacted the ability of the C-H hydrogen to engage in nonclassical C-H...X bonds and drove the conformational properties of benzyl Meldrum's acid, in combination with steric factors, namely A(1,3)-allylic strain. Further understanding of intramolecular C-H...X bonds was gained by characterization of benzyl Meldrum's acids in the solid state, by X-ray analysis, and by the conformation correlated to the observations made in solution.
authors.affiliation: Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. efillion@uwaterloo.ca
authors.forename: Eric
authors.initials: E
authors.lastname: Fillion
authors.forename: Ashraf
authors.initials: A
authors.lastname: Wilsily
authors.forename: Dan
authors.initials: D
authors.lastname: Fishlock
mesh_terms: D001593:Benzyl Compounds / Q000737:chemistry*; D004146:Dioxanes / Q000737:chemistry*; D004987:Ethers / Q000737:chemistry; D006846:Hydrocarbons, Halogenated / Q000737:chemistry; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008968:Molecular Conformation; D012996:Solutions; D013440:Sulfides / Q000737:chemistry
chemical_list: D001593:Benzyl Compounds; D004146:Dioxanes; D004987:Ethers; D006846:Hydrocarbons, Halogenated; D012996:Solutions; D013440:Sulfides; C076489:Meldrum's acid