title: Catalyzing pyramidal inversion: configurational lability of P-stereogenic phosphines via single electron oxidation.
abstract: We report that pyramidal inversion of trivalent phosphines may be catalyzed by single electron oxidation. Specifically, a series of P-stereogenic (aryl)methylphenyl phosphines are shown to undergo rapid racemization at ambient temperature when exposed to catalytic quantities of a single electron oxidant in solution. Under these conditions, transient phosphoniumyl radical cations (R3P(•+)) are formed, and computational models indicate that the pyramidal inversion barriers for these open-shell intermediates are on the order of ∼5 kcal/mol. The observed 10(20)-fold rate enhancement over uncatalyzed pyramidal inversion opens new opportunities for the dynamic stereochemistry of phosphines and may hold additional implications for the configurational stability of P-stereogenic phosphine ligands on high-valent oxidizing transition metals.
authors.affiliation: Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
authors.forename: Kyle D
authors.initials: KD
authors.lastname: Reichl
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Ess
authors.forename: Alexander T
authors.initials: AT
authors.lastname: Radosevich
mesh_terms: D002384:Catalysis; D004583:Electrons; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010720:Phosphines / Q000138:chemical synthesis* / Q000737:chemistry; D011789:Quantum Theory
chemical_list: D010720:Phosphines