Pd(OAc)<sub>2</sub>-Catalyzed Oxidative Coupling Reaction of Benzenes with Olefins in the Presence of Molybdovanadophosphoric Acid under Atmospheric Dioxygen and Air
作者:Masayuki Tani、Satoshi Sakaguchi、Yasutaka Ishii
DOI:10.1021/jo035568f
日期:2004.2.1
The direct oxidativecouplingreaction of benzenes with alkenes bearing an electron-withdrawing group was successfully achieved by the use of Pd(OAc)2/molybdovanadophosphoric acid (HPMoV) as the key catalyst under O2 or air atmosphere. Thus, the reaction of benzene with ethyl acrylate under air (1 atm) assisted by Pd(OAc)2/HPMoV afforded ethyl cinnamate as a major product in satisfactory yield (74%)
A process produces an aromatic compound by bringing an aromatic compound (B) into contact with molecular oxygen (C) in the presence of a catalyst (A) comprising at least one of (A1) a heteropolyacid and/or a salt thereof, and (A2) a mixture of oxoacids and/or salts thereof containing, as a whole, one of P and Si and at least one selected from V, Mo and W to thereby yield another aromatic compound (G) than the aromatic compound (B). The process can produce, for example, a corresponding aromatic hydroxy compound (G1) by allowing the aromatic compound (B) to react with the molecular oxygen (C) further in the presence of a reducing agent (D).
[GRAPHICS]ArH : benzoid and non-benzoid. R = H, CH3, Ph. R-1 = Ph, Co2Et, COMe, CHO, CO2H, CN.The oxidative coupling of arenes with olefins has been performed efficiently in the presence of catalytic amounts of palladium acetate and benzoquinone (BQ) with tert-butyl hydroperoxide as the oxidant in up to 280 turnover numbers (TON). The catalytic system is especially active for the coupling of heterocycles such as furans and indole with activated olefins, The reaction is highly regio- and stereoselective, giving trans-olefins predominantly.