Metal Carbene Dimerization: Versatile Approach to Polyalkynylethenes

摘要

The last years have witnessed an increasing interest in conjugated organic molecules and polymers due primarily to their potential applications as advanced materials, molecular wires, and switches, chemo- and biosensors, nonlinear optics (NLO), organic conductors, etc. The main focus has been on molecules containing an ethene unit, which is surrounded by alkynyl or mixed alkynyl/alkenyl branches, because of their planarity, two-dimensional conjugation, and potential for acetylenic scaffolding. Whereas the area of polyethynylethenes has been a motif of special emphasis, the access to hybrid ethynyl/ethenyl ethenes has been explored to a lesser extent. Despite the fact that some dimerization reactions involving carbenoid species or palladium catalysis have been disclosed, most work has focused on protocols for dimer preparation by multiple C_((sp2))—C_((sp)) and C_((sp))—C_((sp)) coupling processes, which generally require protection/ deprotection steps.