Synthesis, Methanolysis, and Asymmetric Polymerization of meta- and para-substituted Triphenylmethyl Methacrylates

Abstract

Five novel meta- and para-substituted triphenylmethyl methacrylates, diphenyl-m-fluorophenylmethyl methacrylate (m-F1TrMA), m-chlorophenyldiphenylmethyl methacrylate (m-Cl1TrMA), tris(m-chlorophenyl)methyl methacrylate (m-Cl3TrMA), tris(p-chlorophenyl)methyl methacrylate(p-Cl3TrMA), and tris(m-tolyl)methyl methacrylate (m-Me3TrMA), were synthesized: Their solvolysis rates were measured in CDCl3-CD3OD (1:1) by 1H NMR spectroscopy at 35°C. The rates were greatly affected by the substituents. Chlorine and fluorine substituents decreased the rates of the methanolysis and the methyl group accelerated it. These methacrylates were polymerized with chiral anionic initiators, such as (+)-(2S,3S)- or (−)-(2R,3R)-dimethoxy-1,4-bis(dimethylamino)butane (DDB)-N,N′-diphenylethylenediamine monolithium amide (DPEDA-Li) and (−)-sparteine-fluorenyllithium (Sp-FlLi) complexes in toluene at −78°C. DDB-DPEDA-Li complex was more reactive than the Sp-FlLi complex and gave quantitatively optically active, isotactic polymers with one-handed helicity except for p-Cl3TrMA. p-Cl3TrMA did not form a high polymer probably because of the bulkiness of the ester group. The CD spectra of the optically active polymers were different from each other. The copolymerization of p-Cl3TrMA with TrMA by (+)-DDB-DPEDA-Li complex gave a low-molecular-weight copolymer of low optical activity which decreased slowly with time probably because of uncoiling of the helix.