Formation of Conjugated Polynaphthalene via Bergman Cyclization

A series of enediyne containing chiral phthalimides were synthesized through Sonogashira coupling reactions. These enediynes were then subjected to thermal Bergman cyclization under vacuum. Polynaphthalenes with pendant chiral groups were obtained and characterized using GPC, IR spectroscopy, NMR spectroscopy, UV-Vis spectroscopy, and photoluminescence analysis. Under properly optimized conditions, the chirality of chiral directing group was maintained according to CD spectra of final products. After removal of chiral directing groups, weak CD signals representative of main chain chirality were visible. Further modification of the structure of the enediyne compounds will facilitate the synthesis of chiral poly naphthalene through this rather simple way. Extension of the Bergman cyclization to polymer chemistry is promising in the construction of novel polymers with rigid polyarene backbones. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2187-2193, 2010