Precision native polysaccharides from living polymerization of anhydrosugars

Wu, Lianqian; Zhou, Zefeng; Sathe, Devavrat; Zhou, Junfeng; Dym, Shoshana; Zhao, Zhensheng; Wang, Junpeng; Niu, Jia

doi:10.1038/s41557-023-01193-2

Cited by 32 publications

(23 citation statements)

References 39 publications

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“…We began these studies by testing the ability of electron-deficient boranes to activate the C–F bonds of difluorocyclopropenes because of their high Lewis acidity , and their established fluoride ion affinities . In addition, several reports have demonstrated the ability of boranes to cleave C–F bonds in fluoroalkanes. − Upon combining stoichiometric amounts of cyclopropene 1 (1.0 equiv) and B(C 6 F 5 ) 3 (1.0 equiv) in C 6 D 6 (0.7 mL), white needles spontaneously crystallized from the solution over 2 h. X-ray crystallographic analysis of a single crystal of this solid revealed it to be d 5 -triphenylcyclopropenium tris(pentafluorophenyl)fluoroborate ([Ph 2 (C 6 D 5 )C 3 ] + [(C 6 F 5 ) 3 BF] − , 3 ) (45% isolated yield) (Scheme ). Presumably, the salt arose from a Friedel–Crafts addition of C 6 D 6 to fluorodiphenylcyclopropenium ion ( 4 ) generated in situ and then a second C–F bond functionalization from intermediate 6 .…”

Section: Resultsmentioning

confidence: 99%

Borane-Catalyzed C–F Bond Functionalization of gem-Difluorocyclopropenes Enables the Synthesis of Orphaned Cyclopropanes

et al. 2023

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Herein, we disclose an approach to synthesize tertalkyl cyclopropanes by leveraging C−F bond functionalization of gem-difluorocyclopropenes using tris(pentafluorophenyl)borane catalysis. The reaction proceeds through the intermediacy of a fluorocyclopropenium ion, which was confirmed by the isolation of [Ph 2 (C 6 D 5 )C 3 ] + [(C 6 F 5 ) 3 BF] − . We found that silylketene acetal nucleophiles were optimal reaction partners with fluorocyclopropenium ion intermediates yielding fully substituted cyclopropenes functionalized with two α-tert-alkyl centers (63−93% yield). The regioselectivity of the addition to cyclopropenium ions is controlled by their steric and electronic properties and enables access to 3,3-bis(difluoromethyl)cyclopropenes in short order. The resulting cyclopropene products are readily reduced to the corresponding orphaned cyclopropanes under hydrogenation conditions. Quantum chemical calculations reveal the nature of the C−F bond cleavage steps and provide evidence for catalysis by boron and not silylated oxonium ions, though Si−F bond formation is the enthalpic driving force for the reaction.

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Section: Resultsmentioning

confidence: 99%

Borane-Catalyzed C–F Bond Functionalization of gem-Difluorocyclopropenes Enables the Synthesis of Orphaned Cyclopropanes

et al. 2023

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“…Moreover, high-efficiency and facile methodologies to incorporate functional moieties including responsive end-caps into depolymerizable backbones without compromising depolymerization capability requires more efforts . On the other hand, other depolymerizable systems that are not discussed here, including polycarbonates, polyamides, polyurethanes, and polysaccharides, also show widely attainable properties and depolymerizations.…”

Section: Discussionmentioning

confidence: 99%

Emerging Trends in the Chemistry of End-to-End Depolymerization

Deng,

Gillies

2023

JACS Au

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Over the past couple of decades, polymers that depolymerize end-to-end upon cleavage of their backbone or activation of a terminal functional group, sometimes referred to as "self-immolative" polymers, have been attracting increasing attention. They are of growing interest in the context of enhancing polymer degradability but also in polymer recycling as they allow monomers to be regenerated in a controlled manner under mild conditions. Furthermore, they are highly promising for applications as smart materials due to their ability to provide an amplified response to a specific signal, as a single sensing event is translated into the generation of many small molecules through a cascade of reactions. From a chemistry perspective, end-to-end depolymerization relies on the principles of self-immolative linkers and polymer ceiling temperature (T c ). In this article, we will introduce the key chemical concepts and foundations of the field and then provide our perspective on recent exciting developments. For example, over the past few years, new depolymerizable backbones, including polyacetals, polydisulfides, polyesters, polythioesters, and polyalkenamers, have been developed, while modern approaches to depolymerize conventional backbones such as polymethacrylates have also been introduced. Progress has also been made on the topological evolution of depolymerizable systems, including the introduction of fully depolymerizable block copolymers, hyperbranched polymers, and polymer networks. Furthermore, precision sequence-defined oligomers have been synthesized and studied for data storage and encryption. Finally, our perspectives on future opportunities and challenges in the field will be discussed.

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“…The glass transition temperatures ranged from −23 to 67 °C, as the alkyl chain substituents on the LGA core varied from ethyl to n -pentyl. 25…”

Section: Levoglucosan (Lga)mentioning

confidence: 99%

“…The NPs were expected to have low cytotoxicity, which was confirmed using cell viability studies, demonstrating minimal toxicity to HCT116 and HEK293 cells. Recent work by Niu et al 25 reports their approach to precision native polysaccharides through the cationic ringopening polymerisation (cROP) of various 1,6-anhydrosugars based on LGA derivatives. The resulting polysaccharides possessed a tuneable molecular weight and low dispersity using a boron trifluoride etherate catalyst.…”

Section: Minireviewmentioning

confidence: 99%