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Post-functionalization of polyethers by photoinduced C-H amidation via polar-radical relay

2026-01-13T18:01:09Z

Title: Post-functionalization of polyethers by photoinduced C-H amidation via polar-radical relay Author(s): Baek, Seung Beom; Kim, Youngho; Lee, Wongyu; Seo, Sangwon; Kim, Dongwook; Seo, Myungeun; Chang, Sukbok Abstract: The C-H functionalization of polymers enables the direct incorporation of new functional groups into polymer backbones, presenting significant opportunities for the upcycling of commodity polymers. However, developing reactions that achieve selective functionalization while preserving the intrinsic features of polymers and avoiding undesirable structure deformation remains a considerable challenge. In this study, we present a transition metal-free post-functionalization approach for polyethers via a photoinduced alpha-C-H amidation reaction. This strategy provides a route to previously unattainable alpha-amino polyethers, which exhibit distinct physical properties from those of the parent polymer. By leveraging a polar-radical relay mechanism, we effectively incorporate C-N bonds into the polyether backbone while suppressing degradation and cross-linking. Conducted under mild and convenient conditions, this approach demonstrates significant site selectivity at the ethereal alpha-position, even in the presence of other types of C-H bonds, achieving tailed post-functionalization of macromolecules. Furthermore, the present strategy holds promise for broader applications, including the amidative degradation of commodity polymers and transformation of polyethylene glycol (PEG) network.

Real-Time Visualisation of Reaction Kinetics and Dynamics: Single-Molecule Insights into the Iminium-Catalysed Diels-Alder Reaction

2025-12-18T02:40:54Z

Title: Real-Time Visualisation of Reaction Kinetics and Dynamics: Single-Molecule Insights into the Iminium-Catalysed Diels-Alder Reaction Author(s): Park, Minsoo; Ahn, Yongdeok; Cho, Juhyeong; Jang, Juhee; Lee, Wonhee John; Seo, Sangwon; Lee, Sunggi; Seo, Daeha Abstract: Investigation of the fundamental microscopic processes occurring in organic reactions is essential for optimising both organocatalysts and synthetic strategies. In this study, single-molecule fluorescence microscopy was employed to study the Diels-Alder reaction catalysed by a first-generation MacMillan catalyst, providing direct insights into its kinetic dynamics. This reaction proceeds via a series of reversible processes under equilibrium conditions (S -><- IM1 -><- IM2 -> P, IM1 and IM2: N,O-acetal and iminium ion intermediates, respectively). The individual reaction trajectories of single molecules were directly observed in real-time, and the kinetic transitions between the different states were quantitatively analysed using a hidden Markov model, thereby enabling precise determination of the kinetic rate constants and transition probabilities at the single-molecule level. In particular, the unique structural features of the MacMillan catalyst were probed to reveal how specific interactions stabilise the reaction intermediates and influence their kinetic behaviours. These findings highlight the importance of single-molecule fluorescence microscopy in understanding the fundamental mechanisms of organic reactions and guiding the rational design of more effective catalysts.

Synthesis of (Z)-Allylsilanes by Cu-Catalyzed Regioselective Protosilylation of Allenes via a Single-Electron Process

2025-12-18T02:42:23Z

Title: Synthesis of (Z)-Allylsilanes by Cu-Catalyzed Regioselective Protosilylation of Allenes via a Single-Electron Process Author(s): Kim, Min; Kim, Seongha; Lee, Yurim; Lee, Yunmi; Seo, Sangwon; Jung, Byunghyuck Abstract: Hydrosilylation of allenes has gained prominence as an economically viable method for preparing vinylsilanes or allylsilanes. However, development of transition metal (TM)-catalyzed hydrosilylation remains challenging owing to the difficulty in controlling the regioselectivity and stereoselectivity. Specifically, access to (Z)-allylsilanes via first-row TM-catalyzed hydrosilylation is limited by the lack of mechanistic diversity, indicating the need for unprecedented approaches to achieve this valuable yet underexplored chemical space. We herein present the Cu-catalyzed protosilylation of allenes in either organic solvent or water, which affords (Z)-allylsilanes in high yields, with up to >98:2 regioselectivity and (Z)-selectivity. In contrast to conventional TM-catalyzed hydrosilylation or Cu-catalyzed protosilylation, our process involves a single-electron pathway for inserting Cu-SiMe2Ph into the allene. Radical trap experiments and systematic computational studies support the proposed mechanism. Our method is gram-scalable, and the synthetic utility is demonstrated by the preparation of deuterium-incorporated (Z)-allylsilanes through reactions in D2O.

Recent advances in earth-abundant transition metal-catalyzed dihydrosilylation of terminal alkynes

2026-02-16T07:40:13Z

Title: Recent advances in earth-abundant transition metal-catalyzed dihydrosilylation of terminal alkynes Author(s): Lee, Chanmi; Lee, Dohun; Hong, Sung You; Jung, Byunghyuck; Seo, Sangwon Abstract: Over the past few years, earth-abundant transition metal-catalyzed hydrosilylation has emerged as an ideal strategy for the synthesis of organosilanes. The success in this area of research has expanded to the advancements of alkyne dihydrosilylation reactions, offering broadened synthetic applications through the selective installation of two silyl groups. In particular, catalysts based on Fe, Co, and Ni have engendered enabling platforms for mild transformations with a range of distinct regioselectivity. This mini-review summarizes recent advances in this research field, highlighting the unique features of each system from both synthetic and mechanistic perspectives. Copyright © 2024 Lee, Lee, Hong, Jung and Seo.