Isotope effects in hydrogen atom transfer. VII. Benzylic hydrogen abstraction by tert-butoxy and other radicals

Synthesis of Benzylic Alcohols by C–H Oxidation

“…A possible reason for the unusual selectivity for monooxygenation may be a proton coupled electron transfer (PCET) mechanism by mesyloxyl radicals, which differs from the H atom abstraction pathway (HAA) commonly described for reactions of O-centered radicals. 8…”

“…The transformation proceeds with bis­(methanesulfonyl) peroxide ( 1 ) as oxidant and provides benzylic mesylates that are converted to benzylic alcohols under mild conditions (Scheme ). A possible reason for the unusual selectivity for monooxygenation may be a proton coupled electron transfer (PCET) mechanism by mesyloxyl radicals, which differs from the H atom abstraction pathway (HAA) commonly described for reactions of O-centered radicals …”

Carbonylative Formal Cycloaddition between Alkylarenes and Aldimines Enabled by Palladium-Catalyzed Double C–H Bond Activation

“…15 In addition, the hypocholesterolemic reagent 8 could be easily prepared from p-fluorotoluene by carbonylation and hydrogenolysis (Scheme 2). 16 To gain insights into this novel transformation, several mechanistic studies were performed. First, the desired product 3aa was obtained in 53% yield when the standard reaction was catalyzed by Pd(OAc) 2 under otherwise identical conditions, implying that acyl chloride might not be involved in this transformation (Scheme 3a).…”

Isotope effects in hydrogen atom transfers. 9. Neighboring group participation

“…the equilibrium isotope effect k2H/k2T _ H/ k-2H/k_2T Kl /Kl (6) and thus if the reverse isotope effect is unity, the measured isotope effect is the equilibrium isotope effect, which is calculable. The equilibrium isotope effect on reaction 2 reduces to the exchange equilibrium constant for the reaction HR + TBr <=± TR + HBr (7) and the equilibrium constant for reaction 7 can be calculated.…”