Factors Governing Reactivity and Selectivity in Hydrogen Atom Transfer from C(sp³)-H Bonds of Nitrogen-Containing Heterocycles to the Cumyloxyl Radical.

ABSTRACT: A kinetic study of the hydrogen atom transfer (HAT) reactions from nitrogen-containing heterocycles (secondary and tertiary lactams, 2-imidazolidinones, 2-oxazolidinones, and succinimides) to the cumyloxyl radical has been carried out employing laser flash photolysis with ns time resolution. HAT occurs from the C-H bonds that are α to nitrogen, activated by hyperconjugative overlap with the N-C═O π system. In the lactam series, the second-order HAT rate constant (k_H) was observed to decrease by a factor of ∼4 going from the five- and six-membered ring derivatives to the eight-membered ones, a behavior that was rationalized on the basis of a reduced extent of hyperconjugative activation associated to the greater flexibility of the larger rings compared to the smaller ones.

SUBMITTER: Galeotti M 

PROVIDER: S-EPMC9171822 | biostudies-literature | 2022 Jun

REPOSITORIES: biostudies-literature