NAD(P)+-NAD(P)H Models. 53. Proximity Effect of Intramolecular Heteroatom on Reaction Rate

Article abstract of DOI:10.1246/bcsj.58.698

NAD(P)H-model compounds that have a sulfur or oxygen substituent in the molecule have been synthesized and kinetics for the reduction of both substituted and unsubstituted α,α,α-trifluoroacetophenones with these model compounds are studied.Reduction with the heteroatom-containing model compounds proceeds at a slower rate than the reduction with a model without any heteroatom substituents.Furthermore, the dependency of the kinetic isotope effect on the electron-deficiency of the substrate differs.Kinetic parameters reveal tha the retardation caused by the heteroatom is due to the loss of entropy in the initial electron-transfer process.The enthalpic term favors the reduction with the heteroatom-containing model.