M. Newcomb, J. Horner, P. O. Whitted
Nov 3, 1999
Citations
0
Influential Citations
32
Citations
Journal
Journal of the American Chemical Society
Abstract
β-Phosphatoxyalkyl radical reactions were studied experimentally and computationally. The 1,1-dibenzyl-2-(diphenylphosphatoxy)-2-phenylethyl radical (1) reacted to give the migration product 2-benzyl-2-(diphenylphosphatoxy)-1,3-diphenylpropyl radical (2) and the elimination product 2-benzyl-1,3-diphenylallyl radical (3) in a variety of solvents. A modest kinetic solvent effect for reactions of 1 was found. Variable temperature studies in THF and acetonitrile gave Arrhenius functions with similar log A terms; the entropies of activation are ∼−5 eu. A deuterated analogue of radical 1 reacted in THF and acetonitrile with rate constants indistinguishable from those of 1, but the ratio of products 2:3 increased for the deuterated radical requiring kinetic isotope effects (KIEs) in reactions following the rate-limiting step. In aqueous acetonitrile solutions, the β,β-dibenzylstyrene radical cation (4) was detected as a short-lived intermediate, and the rate constants for formation of 3 and 4 indicated that both...