Highly Active Thermomorphic Fluorous Palladacycle Catalyst Precursors for the Heck Reaction; Evidence for a Palladium Nanoparticle Pathway

Abstract

[reaction: see text] The fluorous Schiff base p-Rf8(CH2)3C6H4C(=N(CH2)3Rf8)(CH2)2Rf8 (Rf8 = n-C8F17) is prepared in six steps from p-iodobenzaldehyde and then cyclopalladated (Pd(OAc)2) to give highly effective catalyst precursors for Heck reactions, conducted under homogeneous conditions (DMF, 80-140 degrees C, turnover numbers >10(6)) in the absence of fluorous solvents. Rate, recycling, and other data suggest that the palladacycles serve as sources of palladium nanoparticles, which are the dominant active catalysts.