α-Halogenoacetanilides as hydrogen-bonding organocatalysts that activate carbonyl bonds: fluorine versus chlorine and bromine
Résumé
α-Halogenoacetanilides (X=F, Cl, Br) were examined as H-bonding organocatalysts designed for the double activation of CO bonds through NH and CH donor groups. Depending on the halide substituents, the double H-bond involved a nonconventional CH⋅⋅⋅O interaction with either a HCXn (n=1-2, X=Cl, Br) or a HCAr bond (X=F), as shown in the solid-state crystal structures and by molecular modeling. In addition, the catalytic properties of α-halogenoacetanilides were evaluated in the ring-opening polymerization of lactide, in the presence of a tertiary amine as cocatalyst. The α-dichloro- and α-dibromoacetanilides containing electron-deficient aromatic groups afforded the most attractive double H-bonding properties towards CO bonds, with a NH⋅⋅⋅O⋅⋅⋅HCX2 interaction. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Mots clés
Acetanilides
Bromine
hydrogen bond
Catalysis
Chlorine
Fluorides
hydrogen bonds
lactide
noncovalent interactions
organocatalysis
ring-opening polymerization
acetanilide derivative
fluoride
halogenated hydrocarbon
chemical structure
chemistry
Fluorine
Hydrocarbons
Halogenated
Hydrogen Bonding
Models
Molecular
Quantum Theory