A Kinetic Study of the Reactions of Carbonyl Ylides Formed by the Addition of Fluorenylidene to Ketones

Article abstract of DOI:10.1021/ja00388a026

Fluorenylidene addds to aliphatic ketones to give carbonyl ylide intermediates.With acetone, for example, laser flash photolysis experiments showed that the rate constant for this reaction was 1 x 10⁷ M^-1 s^-1 in acetonitrile solvent.The resulting carbonyl ylide had an absorption spectrum with λ_max = 640 nm in the absence of quenchers underwent ring closure to the corresponding oxirane.The lifetimes, τ_y, for the ring closure reaction are described by the equation -log(τ_y/s) = (13.26 +/- 0.11) - (10.96 +/- 0.12) / θ where θ = 2.3RT kcal mol^-1.The spectra of the carbonyl ylides could be quenched with rate constants of circa 10⁷ M^-1 s^-1 by electron-deficient olefins or oxygen.