Polycondensation of bis(cyanoacetate) and a,10bdihydrobenzofuro [2,3-b] benzofuran-2,9-dicarbaldehyde via Knoevenagel reaction: Synthesis of donor-acceptor polymers containing shoulder-to-shoulder main chains

Compound 5a, 10b-dihydrobenzofuro[2,3-b]benzofuran-2,9-dicarbaldehyde (II) was prepared by two-step reactions from p-cresol and glyoxal. The bis(cyano acetate) monomers (III) were prepared in a high yield by reacting ethyl cya noacetate with the appropriate diol in the presence of tetra-n-butyl titana te. The polymers from II and III were synthesized by Knoevenagel polyconden sation that was first carried out in anhydrous THF and followed by a solid- state polycondensation, and main-chain polymers with good glass transition temperatures in high yield were obtained. The polymerization of II and III afforded polymers TV, which exhibited good solubility in most organic solve nts. The structure of all the monomers and polymers were characterized by c onventional spectroscopic methods. The synthesized polymers contain accepto r groups (cyanide and carbonyl) and a donor group (benzodihydrofuran) in th eir main chain. (C) 2001 John Wiley & Sons, Inc.