Stereospecific Anionic Polymerization and Novel Hydrogen-Transfer Polymerization of α-(Aminomethyl)acrylates Having Unprotected Amino Group

Baraki, Hideo; Habaue, Shigeki

doi:10.1295/polymj.31.1260

Cited by 5 publications

(3 citation statements)

References 19 publications

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“…Thus radical polymerization has been so far the only means to obtain the corresponding polymers with few exceptions such as hydrogentransfer polymerization of α-(aminomethyl)acrylates 16 and N-acryloylurea derivatives with potassium tertbutoxide or 1,8-diazabicyclo [5.4.0]undec-7-ene. [17][18][19][20][21] As a consequence, stereospecific anioic polymerization of acrylamide derivatives have only been known for N, N-disubstituted ones.…”

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confidence: 99%

Synthesis of Highly Isotactic Poly(N-isopropylacrylamide) by Anionic Polymerization of a Protected Monomer

Kitayama

Shibuya

Katsukawa

2002

Polym J

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KEY WORDSN-Isopropylacrylamide / Acrylamide / Trialkylaluminum / Isotactic Polymer / Stereospecific Polymerization / Protected Monomer / Isomerization / Stereoregularity of vinyl polymers often affects significantly their properties and functions, and thus stereospecific polymerization has been important from the view points of both polymer chemistry and industry. In vinyl polymerization ionic and coordination processes have been considered favorable for the stereocontrol, in which proper selection of initiators, catalysts, additives and solvents may provide us with a handle for controlling stereoregularity in a wide variety. For example, we have shown that highly isotactic, syndiotactic, and heterotactic polymethacrylates could be prepared in toluene by using several anionic initiators; tert-butylmagnesium bromide (t-BuMgBr) for isotactic polymerization 1, 2 tert-butyllithium (t-BuLi) / trialkylaluminum (R 3 Al) for syndiotactic one 3, 4 and t-BuLi / bis(2,6-di-tert-butylphenoxy)methylaluminum [MeAl(ODBP) 2 ] for heterotactic one. [5][6][7][8][9][10][11][12][13] Polymers of acrylamide and its derivatives including N-isopropylacrylamide (NIPAm) are widely used in industry, agriculture and medicine due to their remarkable properties including good biocompatibility and low toxicity. 14, 15 Electron-withdrawing nature of amide groups might provide the monomers with potential reactivity favorable for anionic polymerization. However, the presence of acidic hydrogen in acrylamide itself and monosubstituted acrylamide inhibits the anionic vinyl polymerization.Thus radical polymerization has been so far the only means to obtain the corresponding polymers with few exceptions such as hydrogentransfer polymerization of α-(aminomethyl)acrylates 16 and N-acryloylurea derivatives with potassium tertbutoxide or 1,8-diazabicyclo[5.4.0]undec-7-ene. [17][18][19][20][21] As a consequence, stereospecific anioic polymerization of acrylamide derivatives have only been known for N, N-disubstituted ones. 22-28 Nakahama and his coworkers have reported successful stereospecific anionic polymerization of N, N-diethylacrylamide (DEA) in tetrahydrofuran (THF) by careful selection of Lewis-acid additives and counter cations. A syndiotactic poly(DEA) was prepared with alkyllithium initiator [1,1-bis(4 -trimethylsilylphenyl)-3-methylpentyllithium]/diethylzinc (Et 2 Zn), an isotactic one with t-BuMgBr/Et 2 Zn, and a heterotactic one with diphenylmethylpotassium (Ph 2 CHK)/Et 2 Zn. [29][30][31][32][33][34] In 1996, Okamoto and his coworkers 35 reported the anionic polymerization of N, N-diphenylacrylamide with t-BuMgBr in toluene at −78 • C, which gave an isotactic polymer with m diad of 80%. More recently, they also found that, in radical polymerizations of acrylamide and its derivatives, rare-earth metal trifluoromethanesulfonates (triflates) as Lewis-acid additives promoted stereospecific polymerization and, in particular, isotactic poly(NIPAm)s with m diad content of 92% were obtained with lutetium and yttrium triflates in methanol at −20 • ...

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confidence: 99%

Synthesis of Highly Isotactic Poly(N-isopropylacrylamide) by Anionic Polymerization of a Protected Monomer

Kitayama

Shibuya

Katsukawa

2002

Polym J

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“…The synthesis of N-substituted alkyl 2-(aminomethyl)acrylates 12 via substitution reactions of alkyl 2-(bromomethyl)acrylates 11 with primary amines was performed under optimized conditions in analogy with literature procedures (Baraki et al 1999;Habaue et al 1997 hydrobromic acid in dichloromethane to the corresponding hydrobromide salts.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of new functionalized aziridine-2- and azetidine-3-carboxylic acid derivatives of potential interest for biological and foldameric applications

et al. 2011

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A short synthesis of alkyl 2-(bromomethyl)aziridine-2-carboxylates and alkyl 3-bromoazetidine-3-carboxylates was developed involving amination, bromination and base-induced cyclization of alkyl 2-(bromomethyl)acrylates. The aziridines are the kinetically favored cyclization products and could be transformed into 3-bromoazetidine-3-carboxylic acid derivatives via thermal isomerization. The new small-membered azaheterocyclic α-and β-amino acid derivatives contain a bromo-substituted carbon center as a useful moiety for functionalization.Transformation of these functionalized azaheterocycles via nucleophilic substitution with carbon, sulfur, oxygen and nitrogen nucleophiles and via elaboration of the amino and carboxyl group provided a broad range of new conformationally constrained aziridine-2-and azetidine-3-carboxylic acid derivatives which are of interest from a biological point-of-view as well as for applications in the field of foldamers.

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“…Thus, depending on the initiator type and polymerization conditions, linear, branched, hyperbranched, and cyclic microstructures are possible for polyethylene (Scheme 1). 1 Similar irregular Htransfers resulting in complex microstructures can occur for the anionic polymerizations of some vinyl organosilanes, 2−4 α-(aminomethyl)acrylates, 5 and acrylonitriles. 6 In contrast, regioregular isomerizations during propagation are exceedingly rare.…”

Section: ■ Introductionmentioning

confidence: 88%

An Addition–Isomerization Mechanism for the Anionic Polymerization of MesP═CPh₂ and m-XylP═CPh₂

et al. 2018

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We report that the anionic polymerization of P-mesityl and m-xylyl-substituted phosphaalkenes follows an unusual addition–isomerization mechanism. Specifically, the polymerization of ArPCPh2 [Ar = Mes (1a), m-Xyl (1b)] involves the hindered nucleophilic anion intermediate, Ⓟ–P(Ar)–CPh2 –, which undergoes a proton migration from the o-CH3 of the Mes/m-Xyl moiety to the −CPh2 moiety to afford a propagating benzylic anion. This mechanism is supported by the preparation of model compounds MeP(CHPh2)-4,6-Me2C6H2–2-CH2–CPh3 (2a) or MeP(CHPh2)-6-MeC6H3–2-CH2–CPh3 (2b), which were both crystallographically characterized. Polymerization of 1a or 1b in THF solution using n-BuLi (2 mol %) revealed 1H and 13C NMR signals assigned to −CH2– and −CHPh2 groups consistent with an addition–isomerization polymerization mechanism to afford poly(methylenephosphine) 3a or 3b. A large kinetic isotope effect (≤23) was determined for the n-BuLi-initiated polymerization of 1a-d 9 compared to 1a in THF at 50 °C, consistent with C–H (or C–D) activation as the rate-determining step. This C–H activation step was modeled using DFT computations which revealed that the intramolecular proton transfer from the o-CH3 of the Mes moiety to the −CPh2 moiety has an activation energy (E a = +18.5 kcal mol–1). For comparison, this computational value was quite close to the experimentally measured activation energy of propagation ArPCPh2 in THF [E a = 14.0 ± 0.9 kcal mol–1 (1a), 15.6 ± 2.8 kcal mol–1 (1b)].

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Stereospecific Anionic Polymerization and Novel Hydrogen-Transfer Polymerization of α-(Aminomethyl)acrylates Having Unprotected Amino Group

Cited by 5 publications

References 19 publications

Synthesis of Highly Isotactic Poly(N-isopropylacrylamide) by Anionic Polymerization of a Protected Monomer

Synthesis of Highly Isotactic Poly(N-isopropylacrylamide) by Anionic Polymerization of a Protected Monomer

Synthesis of new functionalized aziridine-2- and azetidine-3-carboxylic acid derivatives of potential interest for biological and foldameric applications

An Addition–Isomerization Mechanism for the Anionic Polymerization of MesP═CPh₂ and m-XylP═CPh₂

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Stereospecific Anionic Polymerization and Novel Hydrogen-Transfer Polymerization of α-(Aminomethyl)acrylates Having Unprotected Amino Group

Cited by 5 publications

References 19 publications

Synthesis of Highly Isotactic Poly(N-isopropylacrylamide) by Anionic Polymerization of a Protected Monomer

Synthesis of Highly Isotactic Poly(N-isopropylacrylamide) by Anionic Polymerization of a Protected Monomer

Synthesis of new functionalized aziridine-2- and azetidine-3-carboxylic acid derivatives of potential interest for biological and foldameric applications

An Addition–Isomerization Mechanism for the Anionic Polymerization of MesP═CPh2 and m-XylP═CPh2

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An Addition–Isomerization Mechanism for the Anionic Polymerization of MesP═CPh₂ and m-XylP═CPh₂