No abstract

ABSTRACT:The ability of optical resolution of ( -)-poly(diphenyl-2-pyridylmethyl methacrylate) (PD2PyMA) with highly one-handed helicity was investigated by using it as a chiral stationary phase for high-performance liquid chromatography. The optically active polymer was prepared with an organolithium complex of ( + )-(2S,3S)-dimethoxy-1,4-bis(l-perhydroazepinyl)-butane. When methanol was used as an eluent, PD2PyMA resolved many racemic compounds completely and several binaphthyl derivatives were better resolved than in resolution by optically active poly(triphenylmethyl methacrylate) (PTrMA). When a non-polar eluent, hexane-2-propanol mixture was used, PD2PyMA exhibited higher optical resolving power to several alcohols than PTrMA. This was ascribed to the strong interaction between the 2-pyridy) group of the PD2PyMA and the hydroxy group of the racemate in the non-polar eluent. In order to evaluate the durability of the column in methanol, the solvolysis rates of the monomer and chiral stationary phase were measured. This revealed that PD2PyMA has higher durability in methanol than PTrMA.

Polymerization of diphenyl-2-pyridylmethyl methacrylate was carried out with the complexes of organolithium compounds with 22 chiral ligands. Helix-sense-selectivity of the polymerization was largely affected by a slight structural difference of chiral ligands. ( + )-(S)-2-( 1-Pyrrolidinylmethy1)pyrrolidine was the most effective ligand in producing a one-handed helical polymer with narrow molecular weight distribution.

Asymmetric anionic polymerization of diphenyl-2-pyridylmethyl methacrylate by fluorenyllithium or N,N′-diphenylethylenediamine monolithium amide complex of (S)-(+)-2-(1-pyrrolidinylmethyl)pyrrolidine gave quantitatively an almost purely one-handed helical polymer with narrow molecular weight distribution.