Flipping the Switch on Palladium-Catalyzed Carboiodination: Accessing Kinetic and Thermodynamic Products

A palladium-catalyzed epimerization reaction of stereogenic
alkyl
iodides is reported. This transformation involves use of an air-stable
precatalyst that efficiently epimerizes the C–I bond from the exo to the endo face of [2.2.1] bicyclic
compounds. Mechanistic experiments support the stereoinversion of
the C–I bond via reversible bond formation to generate the
antiproduct bearing an endo iodide. Density functional
theory studies were conducted to support a thermodynamically driven
epimerization. Stoichiometric experiments suggested that irradiation
of isolable alkyl–Pd(II) complexes promoted the C–I
reductive elimination, which could even be applied to C–Br
bond formation.