Novel effect of palladium catalysts on chemoselective oxidation of β-pinene by hydrogen peroxide

Application of PdX2 catalysts (X=Cl-, -OAc, -OCOCF3, acac) for the oxidation of beta-pinene by hydrogen peroxide in methanol is presented. The reactions performed in CH3OH were much faster and more selective than those described in the literature. Moreover, the peculiar tunability of Pd(II) selectivity dependent on the nature of the anionic ligand is highlighted. Although they present different chemoselectivity, PdCl2 and Pd(OAc)(2) were the most active catalysts; high conversions of beta-pinene into allylic oxidation products were obtained (ca. 80 %) when catalyzed by Pd(OAc)(2) and up to ca. 99 % when catalyzed by PdCl2, both in short reaction times (ca. 2 h).