Synthesis and palladium-mediated cross-coupling reaction of cyclic (kyklo-) and open-chain (kentro-) telechelic precursors

A series of uniform-size, cyclic poly (THF)s having a bromophenyl (1a), a pentynoyl (1b) and a phenylboronate (1c) group, together with their open-chain, center-functional counterparts having the relevant functional group (2a and 2b), have been prepared in high yields through the esterification of a hydroxyl group of a cyclic (kyklo-) and an open-chain (kentro-) telechelic precursors. They were subsequently subjected to palladium-mediated, Sonogashira and Suzuki coupling reactions, i.e., 1a and 1b as well as 2a and 2b for the former, and 1a and 1c for the latter, respectively. SEC showed that the Sonogashira process could produce effectively the corresponding cross-coupling products, i.e, an 8-shaped and a 4-armed star polymer, respectively. The Suzuki process, on the other hand, failed to proceed under examined conditions.