Macromolecular Rapid Communications, Vol.34, No.14, 1151-1156, 2013
Synthesis of pi-Conjugated Polymer Consisting of Pyrrole and Fluorene Units by Ru-Catalyzed Site-Selective Direct Arylation Polycondensation
Polycondensation of 1-(2-pyrimidinyl)pyrrole with 2,7-dibromo-9,9-dioctylfluorene via Ru-catalyzed direct arylation gives the corresponding conjugated polymer with a molecular weight of 19 800 in 86% yield. The introduction of directing group, 2-pyrimidinyl substituent, into the pyrrole monomer induces ortho-metalation and provides the site-selective direct arylation polycondensation at the alpha-position of pyrrole unit without the protection of beta-position. The removal of 2-pyrimidinyl substituent on the pyrrole unit proceeds efficiently and results in the enhancement of coplanarity along the main chain of the polymer.
Keywords:directing group;1-(2-pyrimidinyl)pyrrole;polycon-densation;Ru-catalyst;site-selective direct arylation