Study Palladium-catalyzed Coupling Reactions Own Oxygen Oxidation Of Furan And Thiophene Derivatives

Bi(hetero)aryl compounds compounds play an important and wide role in nature, pharmaceuticals and functional materials. As a result, many organic chemists have sought to develop efficient methods for the synthesis of these compounds. Typically, these compounds are synthesized by the cross-coupling of an (hetero)aryl halide halide or pseudohalide with an organometallic reagent, boric acid reagent or electro-rich (hetero)arene, or the homocoupling of two organometallic reagents or two (hetero)arene halides. These methods require the prior preparation of (hetero)arene halides or metal halide reagents by multi-step reactions. On one hand, because the organic metal reagent generally has high reactivity and easily react with water and oxygen, the reaction proceeds in dry oxygen-free atmosphere and needs high operating technique. On the other hand, some (hetero)arene metal reagents are difficult to synthesize, therefore, these methods have great room for improvement on the atom economy, steps economy, operability, and environmental protection.Herein, we reported the first efficient synthesis of the oligofurans(oligothiophenes) compounds by the direct homecoupling of furan(thiophenes) with the C-H activation strategy. The reaction is of complete5-position regioselectivity, catalyzed by palladium(II) and uses oxygen as the sole oxidant, trifluoroacetic acid as additives, dimethyl sulfoxide as solvent. Compared with the traditional method, this method is simple and friendly environmental which have high yield and high atom utilization. It is a new way for the home-coupling of furan(thiophenes).