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611.
612.
Kathleen M. Morrison Dr. Charles S. Yeung Prof. Dr. Mark Stradiotto 《Angewandte Chemie (International ed. in English)》2023,62(23):e202300686
A systematic evaluation of competitive bisphosphine/Ni-catalyzed C−N versus C−O cross-couplings involving model compounds enabled development of hitherto unknown chemoselective O- and N-arylation of amino alcohols with (hetero)aryl chloride electrophiles, without recourse to protection group chemistry. Use of the CyPAd-DalPhos pre-catalyst C2 enabled particularly challenging O-arylation chemoselectivity in amino alcohols featuring branched primary and secondary alkylamine groups, while selective N-arylation was observed in substrates featuring less-hindered linear alkylamine and aniline reacting groups. Useful reaction scope in the (hetero)aryl chloride was achieved throughout, and the ability to conduct such transformations using benchtop handling of materials is demonstrated. 相似文献
613.
Dr. Piret Villo Dr. Andrey Shatskiy Prof. Markus D. Kärkäs Prof. Helena Lundberg 《Angewandte Chemie (International ed. in English)》2023,62(4):e202211952
Alcohols and their derivatives are ubiquitous and versatile motifs in organic synthesis. Deoxygenative transformations of these compounds are often challenging due to the thermodynamic penalty associated with the cleavage of the C−O bond. However, electrochemically driven redox events have been shown to facilitate the C−O bond cleavage in alcohols and their derivatives either through direct electron transfer or through the use of electron transfer mediators and electroactive catalysts. Herein, a comprehensive overview of preparative electrochemically mediated protocols for C−O bond activation and functionalization is detailed, including direct and indirect electrosynthetic methods, as well as photoelectrochemical strategies. 相似文献
614.
Fulai Liu Xutao Gao Rui Shi Prof. Dr. Zhengxiao Guo Prof. Dr. Edmund C. M. Tse Prof. Dr. Yong Chen 《Angewandte Chemie (International ed. in English)》2023,62(11):e202300094
Electro-reforming of Polyethylene-terephthalate-derived (PET-derived) ethylene glycol (EG) into fine chemicals and H2 is an ideal solution to address severe plastic pollution. Here, we report the electrooxidation of EG to glycolic acid (GA) with a high Faraday efficiency and selectivity (>85 %) even at an industry-level current density (600 mA cm−2 at 1.15 V vs. RHE) over a Pd−Ni(OH)2 catalyst. Notably, stable electrolysis over 200 h can be achieved, outperforming all available Pd-based catalysts. Combined experimental and theoretical results reveal that 1) the OH* generation promoted by Ni(OH)2 plays a critical role in facilitating EG-to-GA oxidation and removing poisonous carbonyl species, thereby achieving high activity and stability; 2) Pd with a downshifted d-band center and the oxophilic Ni can synergistically facilitate the rapid desorption and transfer of GA from the active Pd sites to the inactive Ni sites, avoiding over-oxidation and thus achieving high selectivity. 相似文献
615.
M. Sc. Gerlis von Haugwitz B. Sc. Kian Donnelly M. Sc. Mara Di Filippo Dr. Daniel Breite Max Phippard Dr. Agnes Schulze Dr. Ren Wei Dr. Marcus Baumann Prof. Dr. Uwe T. Bornscheuer 《Angewandte Chemie (International ed. in English)》2023,62(18):e202216962
Poly(vinyl alcohol) (PVA) is a water-soluble synthetic vinyl polymer with remarkable physical properties including thermostability and viscosity. Its biodegradability, however, is low even though a large amount of PVA is released into the environment. Established physical-chemical degradation methods for PVA have several disadvantages such as high price, low efficiency, and secondary pollution. Biodegradation of PVA by microorganisms is slow and frequently involves pyrroloquinoline quinone (PQQ)-dependent enzymes, making it expensive due to the costly cofactor and hence unattractive for industrial applications. In this study, we present a modified PVA film with improved properties as well as a PQQ-independent novel enzymatic cascade for the degradation of modified and unmodified PVA. The cascade consists of four steps catalyzed by three enzymes with in situ cofactor recycling technology making this cascade suitable for industrial applications. 相似文献
616.
Dr. Zheng-Yang Gu Dr. Wen-Duo Li Dr. Yan-Lin Li Kun Cui Dr. Ji-Bao Xia 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(1):e202213281
A visible light-induced Co-catalyzed highly regio- and stereoselective reductive coupling of vinyl azaarenes and alkynes has been developed. Notably, Hünig's base together with simple ethanol has been successfully applied as the hydrogen sources instead of commonly used Hantzsch esters in this catalytic photoredox reaction. This approach has considerable advantages for the straightforward synthesis of stereodefined multiple substituted alkenes bearing an azaarene motif, such as excellent regioselectivity (>20 : 1 for >30 examples) and stereoselectivity (>20 : 1 E/Z), broad substrate scope and good functional group compatibility under mild reaction conditions, which has been utilized in the concise synthesis of natural product monomorine I. A reasonable catalytic reaction pathway involving protolysis of the cobaltacyclopentene intermediate has been proposed based on the mechanistic studies. 相似文献
617.
Dr. Qiang Liu Niklas Pfriem Dr. Guanhua Cheng Dr. Eszter Baráth Prof. Yue Liu Prof. Johannes A. Lercher 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(3):e202208693
The intracrystalline ionic environment in microporous zeolite can remarkably modify the excess chemical potential of adsorbed reactants and transition states, thereby influencing the catalytic turnover rates. However, a limit of the rate enhancement for aqueous-phase dehydration of alcohols appears to exist for zeolites with high ionic strength. The origin of such limitation has been hypothesized to be caused by the spatial constraints in the pores via, e.g., size exclusion effects. It is demonstrated here that the increase in turnover rate as well as the formation of a maximum and the rate drop are intrinsic consequences of the increasingly dense ionic environment in zeolite. The molecularly sized confines of zeolite create a unique ionic environment that monotonically favors the formation of alcohol-hydronium ion complexes in the micropores. The zeolite microporous environment determines the kinetics of catalytic steps and tailors the impact of ionic strength on catalytic rates. 相似文献