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1 H NMR (A) (CDCl 3 , 55 °C) and MALDI-TOF-MS (B) spectra of poly(BzF) obtained in asymmetric living cationic polymerization of BzF using CTA1 and (S)-2d.
Source publication
Benzofuran (BzF) is a prochiral, 1,2-disubstituted, unsymmetric cyclic olefin that can afford optically active polymers by asymmetric polymerization, unlike common acyclic vinyl monomers. Although asymmetric cationic polymerization of BzF was reported by Natta et al. in the 1960s, the polymer structure has not been clarified, and there are no repor...
Contexts in source publication
Context 1
... polymer obtained with CTA1 and (S)-2d was then analyzed by 1 H NMR and MALDI-TOF-MS (Figure 2). The proton signals ascribed to the repeating BzF units were relatively sharp, suggesting high stereoregularity, which will be discussed later. ...
Context 2
... terminated by the thiophenol moiety to possess high chain end fidelity, which can be used as macro CTA later. To further investigate the controllability of molecular weight, the feed ratio of BzF to CTA1 was changed ( Figure S2). The M n of the obtained polymers increased in direct proportion to the product of the feed ratio ( [BzF] ...
Citations
... They have polymerized benzofuran (BzF) using a thioether-based cationic RAFT agent and AlCl 3 along with various chiral additives to obtain dual control over molecular weight and optical rotation ( Figure 19). 102 However, the polymers obtained from α-amino acid adducts had very less optical activity. Whereas, the adducts of β-amino acids and their derivatives were found more effective in this case. ...
... [59][60][61][62][63][64][65] In particular, thioacetals or thioethers serve as efficient and reversible chain-transfer agents for the cationic polymerization of vinyl ethers and styrene derivatives and are relatively stable and easy to handle even in air. [60,[64][65][66][67][68][69][70][71][72] In this cationic polymerization, the vinyl monomers are formally inserted into the terminal CÀ S bonds derived from the sulfur compounds via reversible generation of the propagating cationic species based on the DT mechanism. The fast interconversion between the dormant CÀ S species and the propagating cationic species enables the precise control of polymer chain lengths. ...
We report a novel method to synthesize degradable poly(vinyl ether)s with cleavable thioacetal bonds periodically arranged in the main chains using controlled cationic copolymerization of vinyl ethers with a 7‐membered cyclic thioacetal (7‐CTA) via degenerative chain transfer (DT) to the internal thioacetal bonds. The thioacetal bonds, which are introduced into the main chain by cationic ring‐opening copolymerization of 7‐CTA with vinyl ethers, serve as in‐chain dormant species to allow homogeneous propagation of vinyl ethers for all internal segments to afford copolymers with controlled overall and segmental molecular weights. The obtained polymers can be degraded into low‐ and controlled‐molecular‐weight polymers with narrow molecular weight distributions via hydrolysis. Various vinyl ethers with hydrophobic, hydrophilic, and functional pendants are available. Finally, one‐pot synthesis of multiblock copolymers and their degradation into diblock copolymers are also achieved.
The effects of aryl substituents on α,α,α’,α’-tetraaryl-1,3-dioxolane-4,5-dimethanol (TADDOL) ligands were investigated to develop a TADDOL/TiCl 4 system that simultaneously controls the stereoregularity and molecular weight of poly(isobutyl vinyl ether). Substituents were...
Benzo‐fused five‐membered N/O/S heterocyclic compounds, such as indole, benzofuran, and benzothiophene, possessing a single heteroatom, have important applications in medicinal chemistry, agrochemistry, and material chemistry. Metal‐catalysed reactions are well‐established synthetic pathways for the formation of C−X bonds, enabling the direct synthesis of heterocycles. This approach offers advantages over traditional methods, such as fewer steps, increased atom economy, low catalyst loading, regioselectivity, and stereoselectivity. Due to their widespread use in the pharmaceutical industry, the formation of C−N, C−O, and C−S bonds has gained significant attention. This article focusses on the metal‐catalysed synthesis and corresponding mechanistic approaches for N/O/S‐heterocycles, particularly indole, benzofuran, and benzothiophene, reviewing the progress of the past five years and discussing unexplored future opportunities.
Precise control of multiple structural parameters associated with vinyl polymers is important for producing materials with the desired properties and functions. While the development of living polymerization methods has provided a way to control the various structural parameters of vinyl polymers, the concomitant control of their sequence and regioregularity remains a challenging task. To overcome this challenge, herein, we report the living cationic ring‐opening polymerization of hetero Diels–Alder adducts. The scalable and modular synthesis of the cyclic monomers was achieved by a one‐step protocol using readily available vinyl precursors. Subsequently, living polymerization of the cyclic monomers was examined, allowing the synthesis of vinyl polymers while controlling multiple factors, including molecular weight, dispersity, alternating sequence, head‐to‐head regioregularity, and end‐group functionality. The living characteristics of the developed method were further demonstrated by block copolymerization. The synthesized vinyl polymers exhibited unique thermal properties and underwent fast photodegradation even under sunlight.
Precise control of multiple structural parameters associated with vinyl polymers is important for producing materials with the desired properties and functions. While the development of living polymerization methods has provided a way to control the various structural parameters of vinyl polymers, the concomitant control of their sequence and regioregularity remains a challenging task. To overcome this challenge, herein, we report the living cationic ring‐opening polymerization of hetero Diels–Alder adducts. The scalable and modular synthesis of the cyclic monomers was achieved by a one‐step protocol using readily available vinyl precursors. Subsequently, living polymerization of the cyclic monomers was examined, allowing the synthesis of vinyl polymers while controlling multiple factors, including molecular weight, dispersity, alternating sequence, head‐to‐head regioregularity, and end‐group functionality. The living characteristics of the developed method were further demonstrated by block copolymerization. The synthesized vinyl polymers exhibited unique thermal properties and underwent fast photodegradation even under sunlight.
