Synthesis of [2,2’]Bifuranyl‐5,5’‐dicarboxylic Acid Esters via Reductive Homocoupling of 5‐Bromofuran‐2‐carboxylates Using Alcohols as Reductants

Herein, we describe an environmentally benign and cost‐effective protocol for the synthesis of valuable bifuranyl dicarboxylates, starting with α‐bromination of readily accessible furan‐2‐carboxylates by LiBr and K2S2O8. Furthermore, the bromination intermediate product 5‐bromofuran‐2‐carboxylates were then conducted in a palladium‐catalyzed reductive homocoupling reactions in the presence of alcohols to afford bifuranyl dicarboxylates. One of the final products in this protocol, [2,2’]bifuran‐5,5’‐dicarboxylic acid esters, are essential monomers of poly(ethylene bifuranoate), which can be served as an green and versatile alternative polymer for traditional poly(ethylene terephthalate) that is currently common in technical plastics. We developed an environmentally benign protocol for α‐bromination of furan‐2‐carboxylates with LiBr and K2S2O8 in good yields. The resulting 5‐bromofuran‐2‐carboxylates further underwent palladium‐catalyzed reductive homocoupling reactions in alcohols using as reductants to afford [2,2’]bifuran‐5,5’‐dicarboxylic acid esters as the monomers of promising polymer.