Synthesis of novel polymethacrylate bearing an (S)‐(+)‐1‐cyclohexylethyl urea group in the side chain and its chiral recognition ability

Abstract

ABSTRACT:A new chiral methacrylate, (S)-(ϩ)-1-cyclohexylethyl-(2-methacryloyloxyethyl)urea (CEMOU), was synthesized from 2-methacryloyloxyethyl isocyanate (MOI) and (S)-(ϩ)-cyclohexylethylamine. Radical homopolymerization of CEMOU was performed in several solvents to obtain the corresponding chiral polymers having hydrogen bonds based on urea moieties. Specific optical rotations of poly(CEMOU) were slightly changed by the measurement temperature, which may be attributed in part to a change of conformation caused by hydrophobic interaction between the cyclohexyl groups. From the results of radical copolymerization of CEMOU (M 1 ) with styrene (ST, M 2 ) or methyl methacrylate (MMA, M 2 ), monomer reactivity ratios (r 1 , r 2 ) and Alfrey-Price Q-e values were determined: r 1 ϭ 0.89, r 2 ϭ 0.12, Q 1 ϭ 2.45, e 1 ϭ 0.68 for the CEMOU-ST system; r 1 ϭ 0.48, r 2 ϭ 0.18, Q 1 ϭ 8.39, e 1 ϭ 1.97 for the CEMOU-MMA system. The chiroptical property of the poly(CEMOU-co-ST) was slightly influenced by the co-units. Poly(CEMOU)-bonded silica gel as the chiral stationary phase (CSP) was prepared for high-performance liquid chromatography (HPLC). The CSP resolved trans-2-dibenzyl-4,5-di(o-hydroxyphenyl)-1,3-dioxolane in normal phase such as n-hexane/2-propanol by HPLC.

Asymmetric Polymerization

“…However, the CD spectra indicated that chiral induction in the main chain did not take place [148] . Polymerization of methcrylates having urea moiety (RMOU) was also investigated: [151] , and ( R ) -1 -naphthylethyl ( 101 ) [152] (2 -methacryloyloxyethyl)ureas have been used as a monomer. The poly(RMOC) -and poly(RMOU) -based chiral stationary phase resolved some racemic compounds by HPLC [147 -152] .…”

Synthesis and characterization of well‐defined optically active methacrylic diblock copolymers

“…As far as methacrylate‐based polymers are concerned, relatively complex functional moieties such as amino acids,32 1,1′‐binaphthyl,33 urea,34 cyclic pyrrolidinyl moieties or succinimide35 and cholesteryl groups36 have been introduced as side chains to induce optical activity. The synthesis of optically active methacrylic monomers characterized by structural simplicity has not yet been reported.…”