Oxidative arylation of ethylene with benzene catalyzed by Pd(OAc)2/heteropoly acid/O2 system

Abstract

Oxidative arylation of ethylene with benzene was examined by using a Pd(OAc)₂/heteropoly acid/O₂ system under mild conditions. The reaction of benzene with ethylene in the presence of catalytic amounts of Pd(OAc)₂ combined with H₄PMo₁₁VO₄₀·15H₂O (or H₃PMo₁₂O₄₀·30H₂O), AcONa, and dibenzoylmethane under air at 90–120 °C produced oxidative coupling products, styrene and stilbene, in fair yields (up to 167 total turnovers). From the examination of the catalyst performance of Pd(OAc)₂ combined with various heteropoly acids, it was found that the employment of heteropoly acids including molybdenum ion in their structure is very important to obtain high turnover numbers of Pd.