Synthesis of poly(1,4-naphthylene) bearing crown ether side chain by asymmetric oxidative coupling polymerization

Abstract

The oxidative coupling polymerization of racemic-, ( R)-, and ( S)-2,2′,3,3′-tetrahydroxy-1,1′-binaphthyl derivatives bearing a crown ether moiety was carried out in the presence of a Cu(I) or Cu(II) catalyst with various ligands, such as N, N, N′, N′-tetramethylethylenediamine, ( S)-(+)-1-(2-pyrrolidinylmethyl)pyrrolidine, (−)-sparteine [(−)Sp], and ( S)-(−)-2,2′-isopropylidenebis(4-phenyl-2-oxazoline). Methanol-insoluble poly(binaphthyl crown ether) with a molecular weight up to M n=4.1×10 3 was synthesized in moderate yields. Polymerization using (−)Sp proceeded in an S-selective manner; the polymer with the highest negative specific rotation was obtained with the ( S)-monomer. The obtained polymers exhibited characteristic abilities for chiral recognition toward amino acids, such as 2-phenylglycine hydrochloride and 2-phenylglycine methyl ester hydrochloride.