304867-63-8Relevant academic research and scientific papers
Picosecond radical kinetics. Ring openings of phenyl substituted cyclopropylcarbinyl radicals
Newcomb, Martin,Johnson, Cathy C.,Manek, M. Beata,Varick, Thomas R.
, p. 10915 - 10921 (1992)
Rate constants for ring openings of the trans-(2-phenylcyclopropyl)carbinyl radical (1a), the cis-(2-phenylcyclopropyl)carbinyl radical (1b), and the (2,2-diphenylcyclopropyl)carbinyl radical (1c) were studied by competition kinetics using PTOC esters as radical precursors and hydrogen atom transfer trapping from benzeneselenol as the basis reaction. Radical la was studied in two solvents, toluene and THF; the experimental Arrhenius function for ring opening of 1a was log (kr·s) = 13.9 - 33/2.3RT (R in kcal/mol). It is possible that the immediate precursor to 1a, acyloxy radical 3a, suffers a concomitant decarboxylation-ring opening process that competes with simple decarboxylation leading to 1a. The experimental rate constant for ring opening of la at 25°C is 3 × 1011 s-1. Preliminary kinetic studies of radicals 1b and 1c gave Arrhenius functions of log (kr·s) = 13.9 - 3.1/2.3RT and log (kr·s) = 13.1 - 2.0/2.3RT, respectively, and the respective rate constants for ring openings at 25°C are 4 and 5 × 1011 s-1. Rate constants for ring openings of substituted cyclopropylcarbinyl radicals were estimated by Marcus theory using the known rate constants and equilibrium constant for the parent system and expected ΔG° values for the substituted systems. From these results, the estimated rate constants at 25°C for ring opening of 1a and 1b were 1 × 1011 s-1 and that for le was 4 × 1011 s-1. Precursors to radicals 1, such as the corresponding hydrocarbons, represent hypersensitive radical probes that, in principle, can provide unequivocal conclusions regarding the intermediacy of a radical in a reaction.
Intermolecular enolate heterocoupling: Scope, mechanism, and application
DeMartino, Michael P.,Chen, Ke,Baran, Phil S.
supporting information; experimental part, p. 11546 - 11560 (2009/02/03)
This full account presents the background on, discovery of, and extensive insight that has been gained into the oxidative intermolecular coupling of two different carbonyl species. Optimization of this process has culminated in reliable and scalable proto
Laser flash photolysis studies of alkoxyl radical kinetics using 4-nitrobenzenesulfenate esters as radical precursors
Horner, John H.,Choi, Seung-Yong,Newcomb, Martin
, p. 3369 - 3372 (2007/10/03)
(matrix presented) 4-Nitrobenzenesulfenate esters were used as precursors for the generation of alkoxyl radicals under laser flash photolysis conditions. The esters were efficiently cleaved using the Nd:YAG third harmonic (355 nm) to produce alkoxyl radic
