Oxidative coupling of benzenes with α,β-unsaturated aldehydes by the Pd(OAc)2[molybdovanadophosphoric acid/O2 system

The oxidative coupling reaction of benzene with an (x,P-unsaturated aldehyde was examined by the combined catalytic system of Pd(OAc)(2) with molybdovanadophosphoric acid (HPMoV) under atmospheric dioxygen. Thus, the reaction of benzene with acrolein under dioxygen (1 atm) by the use of catalytic amounts of Pd(OAc)(2) and H4PMo11VO40 (.) 26H(2)O in the presence of dibenzoylmethane as, a ligand in propionic acid at 90 degrees C for 1.5 h afforded cinnamaldehyde in 59% yield and beta-phenyleinnamaldehyde in 5% yield. This catalytic system was extended to the direct oxidative coupling through the C-H bond activation of various arenes with acrolein and methacrolein.