Preparation and photochemical study of soluble optically active block copolymethacrylates and azo-containing random copolymethacrylates

A series of soluble optically active block copolymers of trityl methacrylate (TrMA) and cyclohexyldiphenylmethyl methacrylate (CHDPMA) with methyl methacrylate (MMA) and n-butyl methacrylate (n-BuMA) were synthesized using the complex of 9-fluorenyllithium and (S,S)-(+)-2,3-dimethoxy-1,4-bis(dimethylamino)butane as an initiator in toluene at −78°C. Soluble optically active random copolymers derived from TrMA and azo methacrylates, 6-(4-phenylazophenoxy)hexyl methacrylate (PAHM) and 2-(4-phenylazophenoxy)ethyl methacrylate (PAEM), were obtained under similar anionic polymerization conditions. Optical activities of the copolymers largely depended on the weight percentage of TrMA or CHDPMA component in the polymer chains. Solubility and film formability were significantly improved for the copolymers. Irradiation of optically active TrMA–MMA and CHDPMA–MMA block copolymer films containing photoacid, diphenyl-p-tolylsulfonium triflate, causes the partial hydrolysis of bulky esters and results in the conformational randomization of helical chains, which in turn leads to a significant change in optical rotation of the films. Photoisomerization studies of azo-containing random copolymers indicate that the trans to cis isomerization induces the helical conformation racemization in solution. © 1997 John Wiley & Sons, Inc.     

Asymmetric polymerization of triphenylmethyl methacrylate by optically active anionic catalysts

Triphenylmethyl methacrylate (TrMA) was polymerized with two types of asymmetric anionic catalyst, lithium (R)-N-(1-phenylethyl)anilide (LiAn) and (-)-sparteine–butyllithium complex (Sp–BuLi), at ?78°C. Both catalysts yielded optically active polymers. The polymers obtained with LiAn in toluene and tetrahydrofuran (THF) showed specific rotations [α] of from ?50° to ?90° (in THF). The [α] of the polymer obtained with Sp–BuLi in toluene was positive and increased with polymer yield reaching above +300°s, whereas the polymer obtained in THF showed a low [α] (ca. +7°). Gel permeation chromatograms of both polymers obtained with LiAn and Sp–BuLi in THF exhibited rather narrow molecular weight distributions, whereas those obtained in toluene showed at least two or three components with markedly different molecular weights. The circular dichroism (CD) spectrum of the polymer obtained with Sp–BuLi showed strong positive peaks at 208 and 232 nm and a weak band at 250–280 nm; the polymer produced with LiAn showed a similar spectrum with opposite sign. The poly(methyl methacrylate)s derived from these poly(TrMA)s were highly isotactic but showed negligible rotations ([α] ± 2° in toluene). The polymer of high molecular weight showed clear polarization under a polarizing microscope and the low polymer obtained with LiAn appeared to show flow birefringence in chloroform at room temperature.     

(−)-Sparteine: The compound that most significantly influenced my research

A chiral diamine alkaloid, (−)-sparteine (Sp), has been found to be very effective as a ligand for Grignard reagents when used for the enantiomer-selective polymerization of racemic RS-1-phenylethyl methacrylate. The enantiomeric excess of the initially polymerized monomer is 93%, and at about a 60% conversion, nearly optically pure R-monomer is recovered. This enantiomer selectivity is today the highest in polymer chemistry. Triphenylmethyl methacrylate (TrMA) is a unique monomer that gives a highly isotactic polymer even during radical polymerization. When TrMA is polymerized with the Sp complex with n-butyllithium in toluene at −78 °C, an optically active, isotactic polymer [poly(triphenylmethyl methacrylate) (PTrMA)] with a one-handed helical conformation is obtained. The helical structure is maintained even at room temperature in solution. Analogous helical polymethacrylates that show various conformational changes have also been found. One-handed helical PTrMA exhibits high chiral recognition to a variety of racemates as a chiral stationary phase (CSP) for high-performance liquid chromatography. This finding has led to the development of very powerful CSPs based on polysaccharides, such as cellulose and amylose. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4480–4491, 2004     

Anionic copolymerization of optically active α-methylbenzyl methacrylate and trityl methacrylate. I. Reactivity of monomers

The monomer reactivity ratios were determined in the anionic copolymerization of (S)- or (RS)-α-methylbenzyl methacrylate (MBMA) and trityl methacrylate (TrMA) with butyllithium at ?78°C, and the stereoregularity of the yielded copolymer was investigated. In the copolymerization of (S)-MBMA (M₁) and TrMA (M₂) in toluene the monomer reactivity ratios were r₁ = 8.55 and r₂ = 0.005. On the other hand, those in the copolymerization of (RS)-MBMA with TrMA were r₁ = 4.30 and r₂ = 0.03. The copolymer of (S)-MBMA and TrMA prepared in toluene was a mixture of two types of copolymer: one consisted mainly of the (S)-MBMA unit and was highly isotactic and the other contained both monomers copiously. The same monomer reactivity ratios, r₁ = 0.39 and r₂ = 0.33, were obtained in the copolymerizations of the (S)-MBMA–TrMA and (RS)-MBMA–TrMA systems in tetrahydrofuran (THF). The microstructures of poly[(S)-MBMA-co-TrMA] and poly-[(RS)-MBMA-co-TrMA] produced in THF were similar where the isotacticity increased with an increase in the content of the TrMA unit.     

Asymmetric anionic polymerization of (2-fluorophenyl)(4-fluorophenyl)(2-pyridyl)methyl methacrylate leading to a helical polymer

A novel racemic methacrylate, (2-fluorophenyl)(4-fluorophenyl)(2-pyridyl)-methyl methacrylate¹ (2F4F2PyMA), was synthesized and polymerized with chiral complexes of N,N′-diphenylethylenediamine monolithium amide (DPEDA-Li) with (−)-sparteine (Sp), (2S, 3S)-(+)-2,3-dimethoxy-1,4-bis(dimethylamino)butane (DDB), and (S)-(+)-1-(2-pyrrolidinylmethyl)pyrrolidine (PMP) in toluene at −78°C. The monomer showed higher resistance against methanolysis compared with triphenylmethyl methacrylate (TrMA) and several other analogues. In the asymmetric anionic polymerization of 2F4F2PyMA, PMP was found to be a more effective chiral ligand than DDB and Sp and gave quantitatively an optically active polymer with nearly perfect isotacticity. Enantiomer selection was observed in the polymerization of racemic 2F4F2PyMA with the chiral lithium complexes. Chiral recognition ability of the optically active poly(2F4F2PyMA) was examined by an enantioselective adsorption experiment. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2013–2019, 1998     

COPOLYMERIZATION PROCESS OF TRIPHENYLMETHYL METHACRYLATE AND MMA WITH CHIRAL ANIONIC COMPLEX INITIATOR

The copolymerization process of triphenylmethyl methacrylate (TrMA) and methylmethacrylate (MMA) using chiral anionic complex initiator (-) SP-FlLi (Scheme 1) has beenstudied in toluene and THF, respectively. The copolymer obtained in toluene possessed muchhigher specific rotation than that in THF. These copolymers have shown a tendency to a random and a like alternating structure, respectively.     

Polymerization of tert-alkylacetylenes by Mo- and W-based catalysts

Polymerization of three tert-alkylacetylenes (3,3-dimethyl-1-pentyne, 3,3-dimethyl-1-nonyne, 1-adamantylacetylene) by Mo- and W-based catalysts provided new polymers in virtually quantitative yields. In contrast, Ziegler catalysts did not polymerize these monomers. Every polymer had a form of white solid, and had alternating double bonds along the main chain. Though some of poly(3,3-dimethyl-1-pentyne)s contained a toluene-insoluble fraction, the polymer was totally soluble when proper polymerization conditions were chosen. The molecular weights of soluble fractions were as high as 3 × 10⁵. Poly(3,3-dimethyl-1-nonyne) was also partly insoluble in toluene, and the quantity of soluble fraction was less than that of poly(3,3-dimethyl-1-pentyne). The geometric structure of these two polymers could be controlled by the choice of suitable polymerization conditions. Poly(1-adamantylacetylene) was insoluble in any organic solvents. Copolymerization of 1-adamantylacetylene with suitable comonomers afforded soluble copolymers.     

旋光性聚甲基丙烯酸三苯甲酯的合成

<正> 旋光性聚甲基丙烯酸三苯甲酯(PTrMA,A)是一种新型旋光聚合物,其旋光性不是来自结构单元中的手性原子或基因,而是刚性的分子链呈长程单向螺旋构象,使分子链获得手征性的结果.自70年代末问世以来,在改进其合成方法和作为色谱固定相直接拆分手性化合物的应用方面受到人们注意,由于独特的结构,可以设想,如果将它带上特殊     

Helix‐sense‐selective copolymerization of triphenylmethyl methacrylate with chiral 2‐isopropenyl‐4‐phenyl‐2‐oxazoline

The asymmetric induction leading to a one‐handed helix was investigated in the anionic and radical copolymerization of triphenylmethyl methacrylate (TrMA) and (S)‐2‐isopropenyl‐4‐phenyl‐2‐oxazoline ((S)‐IPO), and highly isotactic copolymers with a reasonable optical activity were obtained. In the anionic copolymerization, the optical activity of the obtained copolymers depended on the polarity of solvents, and a highly optically active copolymer was produced in the copolymerization in toluene. The chiral oxazoline monomer functioned not only as a comonomer but also as a chiral ligand to endow the polymer with large negative optical rotation in the copolymerization with TrMA. The copolymers with small positive optical rotation were obtained in THF, indicating that IPO unit may work only as the chiral monomer that dictates the helical sense via copolymerization with TrMA. The isotacticity of the obtained copolymers depended on the contents of TrMA units in the copolymers, but was almost independent of the solvent for copolymerization. In the radical copolymerization, the obtained copolymers exhibited small optical activities. It seemed that the chiral monomer cannot induce one‐handed helical structure of TrMA sequences even if the sequences probably have a high isotacticity. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 441–447     

接枝于聚薄荷基丙烯醇的手性氨基醇的合成及其对Henry反应的不对称催化作用的研究

一种新型的旋光活性的氨基醇类聚合物被合成出来。以旋光活性聚薄荷基乙烯基酮为原料, 将聚薄荷基乙烯基酮用氢化铝锂还原后得到聚薄荷基丙烯醇(poly-MPO),poly-MPO与氢化钠反应后与环氧氯丙烷反应得到固载环氧丙烷的poly-MPO。将固载环氧丙烷的poly-MPO与各种类型的胺反应得到接枝于聚薄荷基丙烯醇的手性氨基醇(poly-MPO)-APO。将其应用在催化不对称Henry反应中得到了高产率、中等选择性的产物。     

Anionic polymerization of N-substituted maleimide. II. Polymerization of N-ethylmaleimide

Anionic polymerization of N-ethylmaleimide (N-EMI) was carried out with potassium t-butoxide, lithium t-butoxide, n-butyllithium, and ethylmagnesium bromide as initiators in THF and in toluene. An almost quantitative yield of poly(N-EMI) was obtained with potassium t-butoxide as initiator in THF in a wide range of polymerization temperatures. Initiators possessing lithium as counter cation produced poly(N-EMI) in slightly lower yields and ethylmagnesium bromide gave the polymer only in less than 35% yield in THF. As a polymerization reaction solvent, THF was preferable for the polymerization of N-EMI compared with toluene with respect to polymer yields. Poly(N-EMI) obtained with anionic initiators exerted unimodal molecular weight distribution. From ¹H- and ¹³C-NMR spectra of poly(N-EMI) anionic polymerization of N-EMI with potassium t-butoxide was revealed to proceed at carbon–carbon double bond. t-Butoxide system was found to have a “living” polymerization character, i.e., the observed average degree of polymerization was in good agreement with the one calculated from the initial molar ratio of N-EMI/initiator and the yield of polymer.     

Synthesis and Properties of Poly(Phenyl Propargyl Ether) and Its Homologues

Abstract

Various para-substituted phenyl propargyl ethers (substitutent = H, OMe, and CN) were synthesized and polymerized by transition metal catalyst systems including MoCl₅, WC1₆, and PdCl₂. The catalytic activity of MoCl₅-based catalysts was greater than that of WCl₆-based catalysts for the present polymerization. The polymer yield increased in the following order: H > OMe > CN, according to substitutents. The [poly-(pheny] propargyl ether) [poly(PPE)] and poly(methoxy phenyl propargyl ether) [poly(OMe-PPE)] obtained are completely soluble in various organic solvents such as chloroform, methylene chloride, THF, and 1,4-dioxane. However, poly(cyanophenyl propargyl ether) [poly(CN-PPE)] is partially soluble in various organic solvents such as those mentioned above. The electrical conductivities of the undoped and iodine-doped polymers and found to be about 10^?13 and 10^?4-10^?5 S/cm, respectively. The solubilities, thermal properties, and morphologies of the resulting polymers were also studied.     

Asymmetric selective polymerization of racemic 1,2-diphenylethyl methacrylate with the ethylmagnesium bromide-(−)-sparteine complex

Asymmetric selective (or stereoelective) polymerization of racemic 1,2-diphenylethyl methacrylate (DPEMA) with ethylmagnesium bromide (EtMgBr)-(?)-sparteine catalyst was studied in toluene at ?78°C. In the polymerization (S) enantiomer was consumed preferentially and the enantiomeric excess of initially polymerized (S) enantiomer was consumed preferentially and the enantiomeric excess of initially polymerized DPEMA was greater than 90%. Optically pure (R) monomer was recovered at about 70% polymer yield. Poly(DPEMA) obtained with EtMgBr-(?)-sparteine complex was highly isotactic. It was found in the polymerization of optically active DPEMA that optical rotation of poly(DPEMA) was dependent on the tacticity and that isotactic and syndiotactic poly(DPEMA)s showed opposite optical rotations. Circular dichroism spectra of the optically active polymers were measured.     

Polymerization of propargylamine and 1,1-diethylpropargylamine by transition metal catalysts

Some polyacetylene derivatives containing an amine functional group were prepared by the polymerization of propargylamine (PA) and 1,1-diethylpropargylamine (DEPA) with various transition metal catalysts. In the polymerization of PA, Mo-based catalysts were more effective than that of W-based catalysts, and organoaluminum compounds, especially EtAlCl₂, were found to be very effective cocatalysts. In the polymerization of DEPA, Mo-and W-based catalyst systems showed a similar catalytic activity. The polymerization easily proceeded in polar solvents such as nitrobenzene and DMF as well as nonpolar aromatic solvents such as chlorobenzene, toluene, etc. The resulting poly(PA) and poly(DEPA) were insoluble in organic solvents regardless of polymerization catalysts but the polymers were found to be stable to air oxidation. Thermogravimetric analyses and thermal transitions of poly(PA) and poly(DEPA) were also studied. © 1992 John Wiley & Sons, Inc.     

Asymmetric radical polymerization and copolymerization of N‐(1‐phenyldibenzosuberyl)methacrylamide and its derivative leading to optically active helical polymers

N‐(1‐Phenyldibenzosuberyl)methacrylamide (PDBSMAM) and its derivative N‐[(4‐butylphenyl)dibenzosuberyl]methacrylamide (BuPDBSMAM) were synthesized and polymerized in the presence of (+)‐ and (?)‐menthols at different temperatures. The tacticity of the polymers was estimated to be nearly 100% isotactic from the ¹H NMR spectra of polymethacrylamides derived in D₂SO₄. Poly(PDBSMAM) was not soluble in the common organic solvents, and its circular dichroism spectrum in the solid state was similar to that of the optically active poly(1‐phenyldibenzosuberyl methacrylate) (poly(PDBSMA)) with a prevailing one‐handed helicity, indicating that the poly(PDBSMAM) also has a similar helicity. Poly(BuPDBSMAM) was optically active and soluble in THF and chloroform. Its optical activity was much higher than that of the poly[N‐(triphenylmethayl)methacrylamide], suggesting that one‐handed helicity may be more efficiently induced on the poly(BuPDBSMAM). The copolymerization of BuPDBSMAM with a small amount of optically active N‐[(R)‐(+)‐1‐(1‐naphthyl)ethyl]methacrylamide, particularly in the presence of (?)‐menthol, produced a polymer with a high optical activity. The prevailing helicity may also be efficiently induced. The chiroptical properties of the obtained polymers were studied in detail. The chiral recognition by the polymers was also evaluated. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1304–1315, 2007     

Reactivity of methacrylates in anionic copolymerization with methyl methacrylate by n-BuLi

Monomer reactivity ratios, r₁ and r₂ were determined in the anionic copolymerizations of methyl methacrylate (MMA, M₁) with ethyl (EtMA), isopropyl (i-PrMA), tert-butyl (t-BuMA), benzyl (BzMA), α-methylbenzyl (MBMA), diphenylmethyl (DPMMA), α,α-dimethylbenzyl (DMBMA), and trityl (TrMA) methacrylates (M₂) by use of n-BuLi as an initiator in toluene and THF at -78°C. The order of the reactivity of the monomers towards MMA anion was DPMMA > BzMA > MMA > EtMA > MBMA > i-PrMA > t-BuMA > TrMA > DMBMA in toluene and TrMA > BzMA > MMA > DPMMA > EtMA > MBMA > i-PrMA > DMBMA > t-BuMA in THF. Except for the extremely low reactivity of TrMA and DPMMA in toluene due to steric hindrance, the order was explained in terms of the polar effect of the ester groups. A linear relationship was found between log (1/r₁) and Taft's σ* values of the ester groups, where the ρ* value was 1.1. The plots of log (1/r₁) vs. the ¹H_a (cis to the carbonyl) and ¹³C_ß chemical shifts of the monomers were also on straight lines. The polymer obtained in the copolymerization of MMA with TrMA in toluene by n-BuLi at -78°C was a mixture of poly-MMA and a copolymer, suggesting that there exist two kinds of growing centers.     

Helix-sense-selective polymerization of phenyl[bis(2-pyridyl)]methyl methacrylate and chiral recognition ability of the polymer

A novel monomer, phenyl[bis(2-pyridyl)]methyl methacrylate (PB2PyMA), was synthesized. The solvolysis rate of PB2PyMA measured in CDCl₃–CD₃ OD [1/1 (v/v)] by ¹H-NMR spectroscopy at 35°C was much smaller than those of triphenylmethyl methacrylate (TrMA) and diphenyl-2-pyridylmethyl methacrylate (D2PyMA). PB2PyMA was anionically polymerized with the complexes of organolithiums with (?)-sparteine (Sp), (S,S)-(+)-and (R,R)?(-)-2,3-dimethoxy-1,4-bis(dimethylamino)butanes[(+)-and (?) -DDB], and (S)-(+)-1-(2-pyrrolidinylmethyl) pyrrolidine (PMP) in toluene at low temperature. The polymers obtained with Sp and DDB complexes showed low optical activity. PMP complexes, particularly that with N,N′-diphenylethylenediamine monolithium amide, were effective in synthesizing a polymer of high optical rotation ([α]²⁵₃₆₅ ～ +1350°) which was comparable to those of poly(TrMA) and poly(D2PyMA) with one-handed helical structure. The optical rotation of poly(PB2PyMA) in a mixture of CHCl₃ and 2,2,2-trifluoroethanol (9/1, v/v) slowly decreased with time. Optically active poly(PB2PyMA) coated on macroporous silica gel was able to resolve racemic compounds as a chiral stationary phase for high-performance liquid chromatography. © 1993 John Wiley & Sons, Inc.     

Diisocyanate route as a convenient method for the preparation of novel optically active poly(amide-imide)s based on N-trimellitylimido-S-valine

A new class of optically active poly(amide-imide)s based on an α-amino acid was synthesized via direct polycondensation reaction of different diisocyanates with a chiral diacid monomer. The step-growth polymerization reactions of N-trimellitylimido-S-valine (TISV) (1) with 4,4′-methylene-bis(4-phenylisocyanate) (MDI) (2) was performed under microwave irradiation, as well as solution polymerization under graduate heating and reflux conditions. The optimized polymerization conditions for each method were performed with tolylene-2,4-diisocyanate (TDI) (3), hexamethylene diisocyanate (HDI) (4), and isophorone diisocyanate (IPDI) (5) to produce optically active poly(amide-imide)s via diisocyanate route. The resulting polymers have inherent viscosities in the range of 0.02-1.10 dL/g. Decomposition temperatures for 5% weight loss (T₅) occurred above 300 °C (by TGA) in nitrogen atmospheres. These polymers are optically active, thermally stable and soluble in amide-type solvents. Some structural characterization and physical properties of this new optically active poly(amide-imide)s are reported.     

Polymerization of 1-Ethynyl-1-Cyclohexanol by Transition Metal Catalysts

Abstract

The polymerization of 1-ethynyl-l-cyclohexanol (ECHO) was carried out by various transition metal catalysts. The Mo- and W-based catalysts gave a relatively low yield of polymer (≤32%). The catalytic activity of Mo-based catalysts was greater than that of W-based catalysts. PdCl₂ was a very effective catalyst for the present polymerization and gave a high yield of polymer. (Ph₃P)₂PdCl₂ and PtCl₂ were also found to be effective catalysts. The structure of the resulting poly(ECHO) was identified by various instrumental methods as a conjugated polyene structure having an α-hydroxycyclohexyl substituent. The poly(ECHO)s were mostly light-brown powders and completely soluble in various organic solvents such as chloroform, chlorobenzene, benzene, DMSO, and THF. Thermal and morphological properties were also studied.     

POLYMERIZATION OF 1-BUTYL-2-TRIMETHYLSILYLACETYLENE BY TRANSITION METAL CATALYSTS

New silicon-containing disubstituted polyacetylene was prepared by the polymerization of BTMSA having two bulky substituents (n-butyl and trimethylsilyl) using transition metal catalysts. The polymerization proceeded in a mild manner and the final polymer yield was generally lower than those of silicon-containing monosubstituted acetylenes by the similar catalyst system. The characterization on the polymer structure revealed that the resulting poly(BTMSA) have a conjugated backbone system, but the polymers have peculiar copolymer composition of poly-(BTMSA) and poly(1-hexyne) due to the spontaneous desilylation during the polymerization. The fluoride-ion induced desilylation of poly(BTMSA) using n-Bu₄N⁺F^? in THF yielded a completely desilylated product, pure poly(1-hexyne).