Discrete multifunctional sequence-defined oligomers with controlled chirality

Abstract

New synthetic strategy leading to discrete poly(triazole-urethane) oligomers with a large range of functional side groups, programmable stereochemistry and sequentiality.

Easily Functionalized and Readable Sequence-Defined Polytriazoles

“…The copper-catalyzed azide–alkyne cycloaddition (CuAAC), recognized as the representative of click reactions, is of unique interest due to its simplicity and high efficiency in achieving robust 1,2,3-triazole skeletons (Scheme A) . On the basis of CuAAC, various ISG and IEG protocols have been successfully established and utilized to build triazole-linked biomimetic oligomers or non-natural sequence-defined polymers in solid or liquid phase. − While 1,4-disubstituted 1,2,3-triazoles are generally provided from CuAAC, the ruthenium-catalyzed azide–alkyne cycloaddition (RuAAC) shows specificity in accessing 1,5-disubstituted isomers, the exploitation of which in the construction of sequence-regulated polymers is still exiguous (Scheme B) . Nevertheless, the triazole rings in the above cases mainly act as connectors to tether subunits, and the extensible azide or alkyne monomers are usually prepared through tedious processes and exhibit limited scopes of side chains.…”

Properties and applications of precision oligomer materials; where organic and polymer chemistry join forces

“…Of particular note is the presence of allyl groups on the backbone which allows secondary functionalization of the oligomers with thiol‐ene chemistry, 88 in turn permitting the generation of BCOs with further sequence diversity. In a similar way, Fernandes and coworkers utilized CuAAc to synthesize discrete oligomers with control over chiral centers along the chain with inclusion of various functional groups along the chain, for example, alkyl, phenyl, pyridyl, hydroxyl, amine, imidazole, and carboxylic acid functions 90 . A combination of thiol–maleimide Michael coupling reactions and orthogonal chain end deprotections based on a retro‐Diels–Alder approach were employed by Zhu to prepare discrete molecular weight materials up to the 128‐mer with the reported purity of the longest oligomer being ~95% 91 .…”

“…In a similar way, Fernandes and coworkers utilized CuAAc to synthesize discrete oligomers with control over chiral centers along the chain with inclusion of various functional groups along the chain, for example, alkyl, phenyl, pyridyl, hydroxyl, amine, imidazole, and carboxylic acid functions. 90 A combination of thiol-maleimide Michael coupling reactions and orthogonal chain end deprotections based on a retro-Diels-Alder approach were employed by Zhu to prepare discrete molecular weight materials up to the 128-mer with the reported purity of the longest oligomer being $95%. 91 With both of these strategies, materials were developed that have no structural analog to traditional polymer classes or biopolymers, highlighting the opportunities in new chemical space that can be explored by the use of robust and orthogonal chemistries.…”

Discrete oligourethanes of sequence-regulated properties – impact of stereocontrol

“…Recently, the field of polymer chemistry has advanced notably, and methods to synthesize uniform polymers with a perfectly defined monomer sequence have been developed. [2][3][4][5] Usually, the methods are based on iterative synthesis that can be performed in solution [6][7][8][9][10] or solid-phase. 11,12 Iterative macromolecule growth enables full control over monomer structure, their sequence, and stereochemistry.…”