Aug 2026· Macromolecules· 0 citations· 28 references
Abstract
The development of efficient polymerization reactions to utilize abundant and inexpensive alkenes for the design of functional polymeric materials is of great significance. Herein, we report the first photocatalytic hydroalkylation polymerization of electron-neutral/rich alkenes with active methylene-containing acetoacetate monomers, enabled by the synergy of photoredox catalysis and hydrogen atom transfer. The rationally designed multifunctional 4CzIPN/(3-Me)PhSH/LiOtBu catalytic system exerts exceptional control over chemoselectivity and regioselectivity, favoring exclusive anti-Markovnikov mono-addition. Endowed with 100% atom economy, mild reaction conditions, broad monomer generality, high yields, and high molecular weight polymers (Mw up to 75.6 kDa), this versatile platform enables the synthesis of structurally diverse polymers from abundant alkene feedstocks—exemplified by oligo(ethylene glycol)-based thermoresponsive polymers with finely tunable LCST behavior and cloud point temperatures. Reactive methine units embedded in the polymer backbone enable versatile post-polymerization modification and multimode structural diversification, while facilitating the construction of chemically recyclable polymer networks via dynamic covalent cross-linking. This work introduces an innovative polymerization paradigm, opening new opportunities for the rational design of stimuli-responsive, functionally versatile, and circular polymeric materials.
Isotactic poly(propylene oxide) (iPPO) is a semicrystalline polyether that has emerged as a high-strength, photodegradable material for marine applications. To improve the accessibility of iPPO, catalysts with higher activity and selectivity are required. Using rational catalyst design informed by computational insights, we developed a flexibly tethered, bimetallic chromium catalyst exhibiting high enantioselectivity (k rel ∼ 100) and unprecedented activity (TOF ∼ 50,000 h–1) for propylene oxide (PO) polymerization. Mechanistic studies reveal that high enantioselectivity originates from increased steric bulk at the ortho position of the salicylimine moiety, which increases steric repulsion between the alkoxide chain end and the ligand in the disfavored transition state. Furthermore, introducing geminal dimethyl groups that rigidify the flexible tether between the two ligand moieties significantly enhances catalyst activity by destabilizing the resting state during polymerization. The catalyst remains active at loadings as low as 0.5 ppm, enabling the synthesis of colorless, tough iPPO.
Bai-Hao Ren, Bryce M Lipinski, L. S. Morris et al.· Journal of the American Chem...· 0 citations
Amido groups are ubiquitous in natural and synthetic polymers and impart critical physiological and physicochemical properties. Conventional access to backbone-amido polymers, polyamides, generally relies on harsh conditions or highly reactive monomers to form amide bonds during polymerization. Here, we report a mild and atom-economic pathway to poly(ether amide)s (PEAs) through the linear step polymerization of diepoxides and amide-bearing primary diols formed in situ by amino alcohols, mostly derived from natural amino acids, and a reactive solvent, γ-butyrolactone. The unique chemoselectivity of the Lewis pair (organo)catalyst enables preferential activation of primary hydroxyl groups toward epoxy ring opening in this multiprotonic system containing secondary/tertiary hydroxyl and amido groups. The trimodular synthesis and abundant starting materials can be well-utilized for structural diversification and property refinement of PEAs, as showcased by their high interfacial performance in two divergent directions: (1) broad-spectrum protein resistance for the more hydrophilic ones, and (2) robust adhesion on various substrates even after 10 reuse cycles or at liquid nitrogen temperature, for the more hydrophobic ones.
Xingpei Hong, Guangzhao Zhang, Junpeng Zhao· Journal of the American Chem...· 0 citations
The use of formate salt as a C1 synthon offers a practical and accessible carboxylating reagent relative to the gaseous alternatives. However, photochemical transient CO2 •– generation from formate and its utilization for carboxylation reactions is mostly restricted to the activated alkenes. Herein, we report a general, photocatalytic platform for the selective anti-Markovnikov hydrocarboxylation of unactivated and activated alkenes using formate salt. The scope of the protocol is demonstrated through the selective hydrocarboxylation of a range of alkenes, independent of the chain length. The control experiments and preliminary mechanistic studies indicate synergy between the tertiary aminium radical cation-mediated hydrogen atom abstraction (HAA) and efficient hydrogen atom transfer (HAT) from the silyl hydride underpin the controlled hydrocarboxylation process. Mechanistic studies also indicate that the radical-polar crossover of the carboxylated alkyl radical can be avoided by the judicious choice of the HAT reagent, providing access to unactivated alkenes in the hydrocarboxylation reaction utilizing formate. This strategy using light energy is mild, robust, and effective for the carboxylation of various alkenes under ambient conditions. Our method enables a modular route for the controlled, steady-state release of CO2 •– using formate, providing a unique pathway for the carboxylation of organic molecules. The application of this protocol has been demonstrated through the large-scale synthesis, synthetic manipulation, and synthesis of isotopically labeled aliphatic carboxylic acids from unactivated and activated alkenes.
Pintu Ghosh, Bikiran Pal, D. Maiti· JACS Au· 0 citations
Living anionic polymerization is a powerful tool for precision polymer synthesis, but typically requires highly reactive organometallic initiators and stringent conditions. Recently, we developed proton transfer anionic polymerization (PTAP) of acrylic monomers, which proceeds via reversible proton transfer reactions between growing anionic species and dormant C–H bonds, offering a milder and more user-friendly alternative. Herein, we report PTAP of 2-vinylpyridine (2VP), an aromatic vinyl monomer with a lower reactivity than acrylic monomers, to expand the scope of PTAP systems. Controlled anionic polymerization of 2VP was achieved using compounds with weakly acidic C–H bonds as initiators or chain-transfer agents (CTAs) in the presence of potassium
tert
-butoxide as base catalysts with cryptand 222 or 18-crown-6 as ligands. Systematic investigations revealed that appropriate CTAs and slow monomer addition were effective for achieving precise molecular weight control. Additionally, this system also exhibited tolerance to
tert
-butyl alcohol, which functioned as a reversible terminator to rapidly regenerate dormant C–H species and to enable more precise molecular weight control. Furthermore, the facile synthesis of poly(
N
,
N
-diethylacrylamide)-
b
-poly(2VP) block copolymers was successfully achieved by sequentially conducting PTAP of acrylic and aromatic vinyl monomers on the basis of common dormant C–H bonds.
Mineto Uchiyama, Koki Sakai, Katsutoshi Sagawa et al.· Polymer journal· 0 citations
Hydroalkylation of alkynes serves as a pivotal strategy for the construction of polysubstituted alkenes. However, its reaction efficiency, substrate scope, and regioselectivity are highly dependent on the structures and reactivities of both the alkynylation reagent and the hydrogen-transfer reagent. This dependence leads to common bottlenecks such as poor structural tunability, low atom economy, and side reactions often caused by the hydrogen-transfer reagent. Herein, we develop a method that combines hydroalkylation of alkynes with decarboxylative ring-opening of cyclic carboxylic acids, where the cyclic carboxylic acid simultaneously serves as the alkynylation reagent and the proton donor. By tuning the substituents and ring size of the cyclic carboxylic acid, diverse substituents can be introduced into the products. In this transformation, the cyclic carboxylic acid undergoes decarboxylative ring-opening via the ligand-to-metal charge transfer (LMCT) process to generate a long-chain alkyl radical, which subsequently adds to an alkyne to give an alkenyl radical. The alkenyl radical is then reduced to an alkenyl anion by Ce(III), and final protonation delivers polysubstituted alkenes. Through cyclic voltammetry, UV-vis absorption spectroscopy, radical trapping, intermediate conversion, and H/D exchange experiments, we demonstrate the involvement of the LMCT process and that the carboxylic acid acts as the sole proton donor.
Yi-Bin Zhang, Shi‐Qing Zhang, Jie Guo et al.· Organic Letters· 0 citations
Despite the broad utility of γ-amino alcohols, their direct and diverse synthesis from cheap, abundant feedstocks remains challenging. Here, by developing a bifunctional single-atom cobalt catalyst supported on hierarchical ordered porous carbon matrix (Co-N4/HPC), it enables hydroxyaminomethylation of nonactivated terminal alkenes with nitroarenes and formaldehyde using HCOOH reductant. This difunctionalization reaction features operational simplicity, high atom/step economy, broad substrate scope, excellent functionality tolerance, high selectivity, and catalyst reusability, offering a practical platform for the general synthesis of γ-arylamino alcohols from bulk chemicals. Notably, the Co-N4 sites mediate mild reduction, while the mesoporous N-doped carbon support enriches formaldehyde via physical adsorption, facilitating the capture of hydroxylamines formed in situ from nitroarene reduction. Subsequent 1,3-dipolar cycloaddition of the resulting nitrones with alkenes, followed by reduction of the cycloadducts, delivers the desired products. The concept of exploiting metal-support synergy for mild reduction and efficient intermediate conversion will open a door to the further development of useful tandem reactions through rational catalyst design.
Wei Liu, Mingkai Liu, Huanfeng Jiang et al.· Journal of the American Chem...· 0 citations