Synthesis of linear and cyclic aromatic peptides with fixed conformation owing to intramolecular hydrogen bonding by condensation polymerization method

Ohishi, Tomoyuki; Suzuki, Takamasa; Niiyama, Tetsurou; Mikami, K.; Yokoyama, Akihiro; Katagiri, Kosuke; Azumaya, Isao; Yokozawa, Tsutomu

doi:10.1016/j.tetlet.2011.10.071

Cited by 13 publications

(10 citation statements)

References 22 publications

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“…Accordingly, CGCP of 4‐amino‐3‐hydroxybenzoic acid ester ( para ‐substituted monomer) or 3‐amino‐4‐hydroxybenzoic acid ester ( meta ‐substituted monomer) in which both the amino and hydroxyl groups are protected, followed by deprotection, should yield well‐defined poly( o ‐hydroxyamide)s, which can be converted to the desired PBOs through thermal cyclodehydration. We recently confirmed that CGCP of 3‐alkylamino‐4‐alkoxybenzoic acid esters proceeds in a controlled manner to afford the corresponding well‐defined poly( m ‐benzamide)s …”

Section: Introductionmentioning

confidence: 76%

Chain‐growth condensation polymerization approach to synthesis of well‐defined polybenzoxazole: Importance of higher reactivity of 3‐amino‐4‐hydroxybenzoic acid ester compared to 4‐amino‐3‐hydroxybenzoic acid ester

Ohta

Niiyama

Yokoyama

et al. 2014

J. Polym. Sci. Part A: Polym. Chem.

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Application of chain‐growth condensation polymerization (CGCP) to obtain well‐defined polybenzoxazole (PBO) was examined. CGCP of both phenyl 3‐{(2‐methoxyethoxy)methoxy (MEM‐oxy)}‐4‐(octylamino)benzoate (1b) (para‐substituted monomer) and phenyl 4‐MEM‐oxy‐3‐(octylamino)benzoate (3b) (meta‐substituted monomer) was examined in the presence of metal disilazide base and phenyl 4‐nitro‐ or methylbenzoate 2 as an initiator. Polymerization of the latter monomer, but not the former, afforded polymer with controlled molecular weight based on the feed ratio of monomer to initiator and with a narrow molecular weight distribution. Accordingly, monomer 3c, in which the octyl group on the amino nitrogen of 3b was replaced with a 4‐(octyloxy)benzyl (OOB) group, was polymerized in the presence of lithium 1,1,1,3,3,3‐hexamethyldisilazide (LiHMDS), phenyl 4‐methylbenzoate (2b), and LiCl in THF at 0 °C to yield poly3c with well‐defined molecular weight (Mn = 4520–9080) and low polydispersity (Mw/Mn ≤ 1.11). Treatment of poly3c with trifluoroacetic acid simultaneously removed the MEM and OOB groups, affording poly(o‐hydroxyamide) (poly4) without scission of the amide linkages. Cyclodehydration of poly4 proceeded at 350 °C to yield PBO (poly5), which was insoluble in organic solvents and acids. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1730–1736

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Section: Introductionmentioning

confidence: 76%

Chain‐growth condensation polymerization approach to synthesis of well‐defined polybenzoxazole: Importance of higher reactivity of 3‐amino‐4‐hydroxybenzoic acid ester compared to 4‐amino‐3‐hydroxybenzoic acid ester

Ohta

Niiyama

Yokoyama

et al. 2014

J. Polym. Sci. Part A: Polym. Chem.

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“…A polymerization technique which is not based on the formation of activated esterswhich is the basic principle in Yamazaki and Ogata-type polycondensations , but on the formation of highly reactive aminyl anions by addition of a strong base is described by Yokozawa et al, the first report on chain-growth polycondensation of aromatic amino acids. , In his group Ohishi et al described the polymerization of N-protected phenyl-3-amino benzoates which possess an alkyloxy side group in the 4-position, and Yoshino et al investigated the polymerization of N -TEGylated phenyl-4-amino benzoates . Both monomers could be polymerized by chain growth condensation polymerization despite the low reactivity of the amino group.…”

Section: Resultsmentioning

confidence: 99%

Bis-TEGylated Poly(p-benzamide)s: Combining Organosolubility with Shape Persistence

et al. 2013

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The synthesis of perfectly planar, bis-substituted aromatic polyamides is reported herein. With highly flexible triethylene glycol chains attached and conformational restriction through intramolecular, bifurcated hydrogen bonds these are among the most shape-persistent yet organo-soluble polymers to date. Starting from 4-nitrosalicylic acid, our group developed a route to phenyl-2,5-bis-TEGylated aminobenzoate, which could be polymerized by addition of lithium bis(trimethylsilyl)amide (LiHMDS). Since this technique has not been applied to step-growth polycondensations of polyaramides so far, the influence of two different solvents and an N-protective group was investigated. Therefore, substituted phenyl aminobenzoate derivatives carrying a free amine or an N-protective group have been polymerized. Additionally, the tendency for self-assembly of the readily soluble bis-TEGylated poly(p-benzamide) was observed by transmission electron microscopy (TEM) in the dried state. Dynamic light scattering (DLS) measurements of chloroform solutions did not indicate the formation of aggregates. Thus, intermolecular interactions, which other aromatic polyamides typically exhibit, are prevented. The access to bis-substituted, entirely rigid poly(p-benzamide)s via this new polycondensation method paves the way for exciting new structures in materials science and supramolecular chemistry.

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“…meta -Substituted phenylene monomers undergo CGCP, leading to polyamides under optimized conditions, − although the inductive effect is less efficiently transmitted, compared to the resonance effect (Table ). Monomer 5 with a methoxyethoxymethyl (MEM)-protected hydroxyl group and OOB-protected amino group afforded the corresponding polyamide, although the para counterpart was hardly polymerized.…”

Section: Cgcp Based On the Substituent Effectmentioning

confidence: 99%

Transformation of Step-Growth Polymerization into Living Chain-Growth Polymerization

2015

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Synthesis of linear and cyclic aromatic peptides with fixed conformation owing to intramolecular hydrogen bonding by condensation polymerization method

Cited by 13 publications

References 22 publications

Chain‐growth condensation polymerization approach to synthesis of well‐defined polybenzoxazole: Importance of higher reactivity of 3‐amino‐4‐hydroxybenzoic acid ester compared to 4‐amino‐3‐hydroxybenzoic acid ester

Chain‐growth condensation polymerization approach to synthesis of well‐defined polybenzoxazole: Importance of higher reactivity of 3‐amino‐4‐hydroxybenzoic acid ester compared to 4‐amino‐3‐hydroxybenzoic acid ester

Bis-TEGylated Poly(p-benzamide)s: Combining Organosolubility with Shape Persistence

Transformation of Step-Growth Polymerization into Living Chain-Growth Polymerization

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