Synthesis and Ring-Opening Metathesis Polymerization of o-Dialkoxy Paracyclophanedienes

The highly strained ortho-diethylhexyloxy [2.2]paracyclophane-1,9-diene (M1) can be synthesized by ring contraction of a dithia[3.3]paracyclophane using a benzyne-induced Stevens rearrangement. This paracyclophanediene undergoes ring-opening metathesis polymerization to give well-defined 2,3-dialkoxyphenylenevinylene polymers with an alternating cis/trans alkene stereochemistry and controllable molecular weight. Fully conjugated block copolymers with electron-rich and electron-deficient phenylene vinylene polymer segments can be prepared by sequential monomer additions. These polymers can be readily isomerized to the all-trans stereochemistry polymer. The optical and electrochemical properties of these polymers were investigated by theory and experiment.