Synthesis of Novel Chiral Poly(methacrylate)s Having Urea Moieties and (S)-Methylbenzyl or l-Phenylalanine Methyl Ester Groups and Their Chiral Recognition Abilities

Abstract

ABSTRACT:New chiral methacrylates, (S )-methylbenzyl methacryloyloxyethyl urea (MBMOU) and (S )-methoxycarbonylbenzylmethyl methacryloyloxyethyl urea (MCMOU) were synthesized from 2-(methacryloyloxy)ethyl isocyanate (MOI) and (S )-methylbenzylamine and L-phenylalanine methyl ester, respectively. Radical polymerizations of MBMOU and MCMOU were performed under several conditions to obtain the corresponding polymers whose specific optical rotations ([α] 25 435 ) were −13.5• to −10.9• and 30.8• to 31.5• , respectively. From the results of radical copolymerizations of RMOU (MBMOU and MCMOU, M 1 ) with styrene (ST, M 2 ) or butyl methacrylate (BMA, M 2 ), monomer reactivity ratios (r 1 , r 2 ) and Alfrey-Price Q-e were determined. The chiroptical properties of poly(MBMOU-co-M 2 )s were strongly influenced by co-units. Poly(RMOU)-bonded-silica gel as chiral stationary phase (CSP) was prepared for high performance liquid chromatography (HPLC). The CSPs resolved some racemates such as ketoprofen and ethyl mandelate. The enantiorecognition ability may be based on higher-ordered structures of the polymer. KEY WORDS 2-(Methacryloyloxy)ethyl isocyanate / Radical Polymerization / Monomer Reactivity Ratios / Chiral Stationary Phase / Optical Resolution / 2-(Methacryloyloxy)ethyl isocyanate (MOI) is a bifunctional monomer with both a reactive isocyanate group and a polymerizable double bond, and is convenient and widely used for crosslinking agents and materials for molecular design of new polymers. 1 Many kinds of MOI derivatives have been synthesized from several alcohol and amine compounds and polymerized. 2 MOI is also useful for preparation of macromonomer. 3 We synthesized and polymerized Nsubstituted maleimide (RMI) macromonomers and examined from the view point of thermal stability of the polymers obtained. 4 However there have been few reports on synthesis of MOI derivatives bearing an optically active group. Bamford et al. 5 synthesized MOI derivatives from α-amino acid and D-glucosamine, and examined applications of the polymers to blood compatibility. Chiral stationary phase (CSP) for high performance liquid chromatography (HPLC) was prepared from MOI and cyclodextrin. 6 To our knowledge, no chiroptical properties of MOI derivatives with optically active groups have been reported. Thus, we lately reported on synthesis and polymerizations of some chiral methacryloyloxyethyl carbamates (RMOC) from MOI and chiral alcohols such as cholesterol, L-menthol, amino acid derivatives, and 2-hydroxy-2 -methoxy-1,1 -binaphthalene, and chiroptical properties of the polymers. [7][8][9] Recently, a wide variety of CSPs have been developed for the separation of enantiomers by HPLC. 10 Although many kinds of synthetic chiral polymers have been applied to the CSPs, there have been few reports on preparation of CSPs for HPLC from poly(methacrylate)s bearing a chiral pendant group. 11 The reason may be that low chiral recognition ability of the chiral pendant group used and/or the absence of stable higher-ordered structures of the...

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

“…A typical chromatogram of the resolution of racemate 7 on CSP is shown in Figure 9. In a previous work, 4 the CSP prepared from poly{(s)-methylbenzyl-(2-methacryloyloxyethyl) urea[MBMOU]}-bearing (S)-methylbenzyl urea groups could resolve racemate 2 in normal phase. Table III shows that racemate 7 was not resolved using 20% 2-propanol in n-hexane as eluent but was resolved using 10% and 5% 2-propanol in n-hexane as eluent.…”

“…[1][2][3][4] MOI is a bifunctional monomer with both a reactive isocyanate group and a polymerizable double bond; it is convenient and widely used for crosslinking agents and materials for the molecular design of new polymers. 5 Many kinds of MOI derivatives have been synthesized from several alcohols and amino compounds and polymerized.…”

“…13 We have previously reported on the preparation of new CSPs with chiral polymethacrylate having urethane or urea bonds in the side chain and their chiral recognition abilities by HPLC. [2][3][4] Miyano et al…”

“…The authors investigated synthesis and polymerizations of some chiral methacrylates from 2‐methacryloyloxy isocyanate (MOI) and chiral alcohols or amines such as cholesterol, L ‐menthol, amino acid derivatives, 2‐hydroxy‐2′‐methoxy 1,1′‐binaphthalene, ( S )‐methylbenzylamine, and L ‐phenylalanine methyl ester and the chiroptical properties of these polymers 1–4. MOI is a bifunctional monomer with both a reactive isocyanate group and a polymerizable double bond; it is convenient and widely used for crosslinking agents and materials for the molecular design of new polymers 5.…”

“…This may be because of the low chiral recognition ability of the chiral pendant group used and/or the absence of stable higher‐order structures of the polymers 13. We have previously reported on the preparation of new CSPs with chiral polymethacrylate having urethane or urea bonds in the side chain and their chiral recognition abilities by HPLC 2–4. Miyano et al14 synthesized optically active polymethacrylate bearing a 1,1′‐binaphthalene moiety as the pendant group and investigated the optical resolution ability as a chiral adsorbent for HPLC.…”