Solvent-free cyclopalladation on silica gel

Tertiary, secondary and primary benzylamines, as well as structurally different oxazolines readily reacted with Pd(OAc)2 on silica gel to form cyclopalladated complexes containing a five or six-membered palladacycle with a (sp2)C–Pd or (sp3)C–Pd bond. The complexes were obtained in 45–98% yield, which is comparable with or exceeds the yields reported for preparation of the same compounds in solution. Aliphatic (sp3)C–H bond activation took place in the cyclopalladation of (S)-2-tert-butyl-4-phenyl-2-oxazoline on SiO2 leading to the exclusive formation of the corresponding endo palladacycle, whereas two products were reported for the same reaction performed in AcOH.