Synthesis of perfluorobiphenyl tetracarboxylic acids via the CuCl2-assisted homocoupling of organozinc reagents

New organozinc reagents were obtained from ethyl esters of tetrafluorophenylene dicarboxylic acids in the reaction with Zn and SnCl₂ in DMF. Tetraethyl perfluorobiphenyl tetracarboxylates were synthesized from these organozinc reagents under the action of CuCl₂ and then were hydrolyzed into perfluorobiphenyl tetracarboxylic acids.