Polymethylenes Containing [2.2]Paracyclophane in the Side Chain

The synthesis of π-stacked polymers based on a polymethylene skeleton containing [2.2]paracyclophane in the side chain by the BF3-catalyzed polymerization of 4-diazomethyl[2.2]paracyclophane was reported. Chiral as well as racemic 4-diazomethyl[2.2]paracyclophane monomers were used to obtain optically active polymethylene. [2.2]Paracyclophane (1) was brominated by a Fe catalyst and then reacted with n-BuLi and DMF to obtain 4-formyl[2.2] paracyclophane (3) in high yield. The structures of polymers (rac)-6, (Rp)-6, and (Sp)-6 were confirmed by 1H and 13C NMR spectra in CDCl3, and their spectra were identical irrespective of the chirality. Thermogravimetric analysis (TGA) of polymer (rac)-6 revealed that its weight decreased by the following two processes in air. Optically active polymethylenes (Rp)-6 and (Sp)-6 exhibited an intense and mirror-image Cotton effect, while the optically inactive polymer (rac)-6 did not exhibit any peaks in CHCl3 solution.