Direct N-substituted N-thiocarboxyanhydride polymerization towards polypeptoids bearing unprotected carboxyl groups

Synthesis of poly(α-amino acid)s bearing carboxyl groups is a critical pathway to prepare biomaterials to simulate functional proteins. The traditional approaches call for carboxyl-protected monomers to prevent degradation of monomers or wrong linkage. In this contribution, we synthesize N -carboxyp...

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Bibliographic Details
Published in:Communications chemistry 2020-10, Vol.3 (1), p.144, Article 144
Main Authors: Zheng, Botuo, Bai, Tianwen, Ling, Jun, Sun, Jihong
Format: Article
Language:English
Subjects:
639/301/54/989
639/638/455/941
Adhesive strength
Amines
Biomedical materials
Block copolymers
Carboxylic acids
Chemistry
Chemistry and Materials Science
Chemistry/Food Science
Copolymerization
Density functional theory
Dimers
Glycine
Monomers
Polymerization
Reagents
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Summary:Synthesis of poly(α-amino acid)s bearing carboxyl groups is a critical pathway to prepare biomaterials to simulate functional proteins. The traditional approaches call for carboxyl-protected monomers to prevent degradation of monomers or wrong linkage. In this contribution, we synthesize N -carboxypentyl glycine N -thiocarboxyanhydride (CPG-NTA) and iminodiacetic acid N -thiocarboxyanhydride (IDA-NTA) without protection. Initiated by amines, CPG-NTA directly polymerizes into polyCPG bearing unprotected carboxyl groups with controlled molecular weight (2.8–9.3 kg mol −1 ) and low dispersities (1.08–1.12). Block and random copolymerizations of CPG-NTA with N -ethyl glycine N -thiocarboxyanhydride (NEG-NTA) demonstrate its versatile construction of complicated polypeptoids. On the contrary, IDA-NTA transforms amines into cyclic IDA dimer-capped species with carboxyl end group in decent yields (>89%) regio-selectively. Density functional theory calculation elucidates that IDA repeating unit is prone to cyclize to be the six-membered ring product with low ΔG . The polymer is a good adhesive reagent to various materials with adhesive strength of 33–229 kPa. Synthetic polymers bearing carboxylic acid pendants typically require the use of protecting group transformations to access. Here direct polymerization of N-carboxypentyl N-thiocarboxyanhydride derivatives offers access to carboxypolypeptide analogs while avoiding undesired side reactions.
ISSN:2399-3669
2399-3669
DOI:10.1038/s42004-020-00393-y