Pub Date : 2024-12-18DOI: 10.1021/acscatal.4c06895
Mattis Damrath, Tarek Scheele, Daniel Duvinage, Tim Neudecker, Boris J. Nachtsheim
Herein, we present the synthesis of chiral triazole-based diaryliodonium salts and their application as monodentate asymmetric iodine(III) derivates in halogen bond (XB) catalyzed reactions. These potential Lewis acids were successfully benchmarked in the vinylogous Mannich reaction of cyanomethyl coumarin with isatin-derived ketimine to obtain the addition product in up to 99% yield and >99:1 e.r. Furthermore, these halogen bond catalysts allowed an efficient functionalization of ketimines with various alcohols toward N,O-acetals in up to 99% yield and 90:10 e.r. Additionally, we studied the origin of the enantioselectivity based on density functional theory (DFT) and the catalyst crystal structure. These unveiled an approach of asymmetric induction facilitated by using σ-hole stabilized chiral moieties in iodine(III)-based catalysts, predominantly predicated upon XB activation.
{"title":"Chiral Triazole-Substituted Iodonium Salts in Enantioselective Halogen Bond Catalysis","authors":"Mattis Damrath, Tarek Scheele, Daniel Duvinage, Tim Neudecker, Boris J. Nachtsheim","doi":"10.1021/acscatal.4c06895","DOIUrl":"https://doi.org/10.1021/acscatal.4c06895","url":null,"abstract":"Herein, we present the synthesis of chiral triazole-based diaryliodonium salts and their application as monodentate asymmetric iodine(III) derivates in halogen bond (XB) catalyzed reactions. These potential Lewis acids were successfully benchmarked in the vinylogous Mannich reaction of cyanomethyl coumarin with isatin-derived ketimine to obtain the addition product in up to 99% yield and >99:1 e.r. Furthermore, these halogen bond catalysts allowed an efficient functionalization of ketimines with various alcohols toward <i>N,O</i>-acetals in up to 99% yield and 90:10 e.r. Additionally, we studied the origin of the enantioselectivity based on density functional theory (DFT) and the catalyst crystal structure. These unveiled an approach of asymmetric induction facilitated by using σ-hole stabilized chiral moieties in iodine(III)-based catalysts, predominantly predicated upon XB activation.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"271 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142849840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-17DOI: 10.1021/acscatal.4c05134
Georgios Giannakakis, Marc Eduard Usteri, Aram Bugaev, Andrea Ruiz-Ferrando, Dario Faust Akl, Núria López, Serena Fantasia, Kurt Püntener, Javier Pérez-Ramírez, Sharon Mitchell
Buchwald–Hartwig (BH) aminations are crucial for synthesizing arylamine motifs in numerous bioactive molecules and fine chemicals. While homogeneous palladium complexes can be effective catalysts, their high costs and environmental impact motivate the search for alternative approaches. Heterogeneous palladium single-atom catalysts (SAC) offer promising recoverable alternatives in C–C cross-couplings. Yet their use in C–N couplings remains unexplored, and mechanistic insights into amine coupling with aryl halides over solid surfaces that could guide catalyst design are lacking. Here, we demonstrate that palladium atoms coordinated to well-defined heptazinic cavities of graphitic carbon nitride (Pd1@C3N4) deliver practically relevant yields for BH couplings across various aryl halides and amines, exhibiting persistent activity and negligible leaching over several cycles. Notably, Pd1@C3N4 shows comparable or superior activity with certain aryl chlorides to bromides, alongside high chemoselectivity for amines over amides. In situ X-ray absorption spectroscopy analyses supported by density functional theory simulations identify the concerted role of the ligand and the C3N4 host in determining the performance, with a Pd(II) nominal oxidation state observed under all coupling conditions. Complementary structural and kinetic studies highlight a distinct reaction mechanism than that typically reported for homogeneous catalysts. These findings offer key insights for designing recyclable SAC for BH coupling, setting the basis for extending the scope toward more complex industrial targets.
{"title":"Reactivity and Mechanism of Recoverable Pd1@C3N4 Single-Atom Catalyst in Buchwald–Hartwig Aminations","authors":"Georgios Giannakakis, Marc Eduard Usteri, Aram Bugaev, Andrea Ruiz-Ferrando, Dario Faust Akl, Núria López, Serena Fantasia, Kurt Püntener, Javier Pérez-Ramírez, Sharon Mitchell","doi":"10.1021/acscatal.4c05134","DOIUrl":"https://doi.org/10.1021/acscatal.4c05134","url":null,"abstract":"Buchwald–Hartwig (BH) aminations are crucial for synthesizing arylamine motifs in numerous bioactive molecules and fine chemicals. While homogeneous palladium complexes can be effective catalysts, their high costs and environmental impact motivate the search for alternative approaches. Heterogeneous palladium single-atom catalysts (SAC) offer promising recoverable alternatives in C–C cross-couplings. Yet their use in C–N couplings remains unexplored, and mechanistic insights into amine coupling with aryl halides over solid surfaces that could guide catalyst design are lacking. Here, we demonstrate that palladium atoms coordinated to well-defined heptazinic cavities of graphitic carbon nitride (Pd<sub>1</sub>@C<sub>3</sub>N<sub>4</sub>) deliver practically relevant yields for BH couplings across various aryl halides and amines, exhibiting persistent activity and negligible leaching over several cycles. Notably, Pd<sub>1</sub>@C<sub>3</sub>N<sub>4</sub> shows comparable or superior activity with certain aryl chlorides to bromides, alongside high chemoselectivity for amines over amides. In situ X-ray absorption spectroscopy analyses supported by density functional theory simulations identify the concerted role of the ligand and the C<sub>3</sub>N<sub>4</sub> host in determining the performance, with a Pd(II) nominal oxidation state observed under all coupling conditions. Complementary structural and kinetic studies highlight a distinct reaction mechanism than that typically reported for homogeneous catalysts. These findings offer key insights for designing recyclable SAC for BH coupling, setting the basis for extending the scope toward more complex industrial targets.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"19 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142840955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-17DOI: 10.1021/acscatal.4c05289
Zhongyao Zhang, Feiting Zhang, Zhongxin Song, Lei Zhang
Metal-free carbon materials functionalized with pyridinic nitrogen groups exhibit promising electrocatalytic activity for the oxygen reduction reaction (ORR). However, not all pyridinic nitrogen groups are equally active for the ORR, which remains ambiguous and requires rigorous quantification and differentiation by their basicity. Here, we introduce the potentiometric titration method for identifying and quantifying nitrogen-containing groups on carbon materials by their Lewis basicity and reactivity in characteristic tests. Various carbon materials are functionalized with nitrogen heteroatoms. Potentiometric titration, X-ray photoelectron spectroscopy (XPS), and elemental analysis suggest that a significant amount of pyridinic nitrogen groups are buried within the bulk structures and cannot be accessed by protons and oxygen molecules. Besides, pyridinic nitrogen functions located adjacent to other nitrogen atoms exhibit weaker basicity due to strong inductive or resonance effects, resulting in a negligible contribution to the ORR activity. ORR measurements under alkaline conditions suggest that the titratable pyridinic nitrogen groups are essential for the active site (or site pair), and kinetic current density is directly proportional to the density of titratable pyridinic nitrogen groups. Furthermore, the turnover frequency for the ORR increases with the Lewis basicity of the pyridinic nitrogen groups for all investigated carbon materials in alkaline and acidic conditions. Density functional theory (DFT) calculations suggest that the ORR occurs on the carbon atoms adjacent to pyridinic nitrogen groups. Pyridinic nitrogen with a higher Lewis basicity can affect adjacent carbon atoms more efficiently, which stabilizes the key intermediates for the ORR and decreases the activation barrier. This work provides an informative and convenient way for characterizing nitrogen-containing groups on carbon materials, especially in quantifying the active pyridinic nitrogen sites for the ORR.
{"title":"Oxygen Reduction Reaction on Pyridinic Nitrogen-Functionalized Carbon: Active Site Quantification and Effects of Lewis Basicity","authors":"Zhongyao Zhang, Feiting Zhang, Zhongxin Song, Lei Zhang","doi":"10.1021/acscatal.4c05289","DOIUrl":"https://doi.org/10.1021/acscatal.4c05289","url":null,"abstract":"Metal-free carbon materials functionalized with pyridinic nitrogen groups exhibit promising electrocatalytic activity for the oxygen reduction reaction (ORR). However, not all pyridinic nitrogen groups are equally active for the ORR, which remains ambiguous and requires rigorous quantification and differentiation by their basicity. Here, we introduce the potentiometric titration method for identifying and quantifying nitrogen-containing groups on carbon materials by their Lewis basicity and reactivity in characteristic tests. Various carbon materials are functionalized with nitrogen heteroatoms. Potentiometric titration, X-ray photoelectron spectroscopy (XPS), and elemental analysis suggest that a significant amount of pyridinic nitrogen groups are buried within the bulk structures and cannot be accessed by protons and oxygen molecules. Besides, pyridinic nitrogen functions located adjacent to other nitrogen atoms exhibit weaker basicity due to strong inductive or resonance effects, resulting in a negligible contribution to the ORR activity. ORR measurements under alkaline conditions suggest that the titratable pyridinic nitrogen groups are essential for the active site (or site pair), and kinetic current density is directly proportional to the density of titratable pyridinic nitrogen groups. Furthermore, the turnover frequency for the ORR increases with the Lewis basicity of the pyridinic nitrogen groups for all investigated carbon materials in alkaline and acidic conditions. Density functional theory (DFT) calculations suggest that the ORR occurs on the carbon atoms adjacent to pyridinic nitrogen groups. Pyridinic nitrogen with a higher Lewis basicity can affect adjacent carbon atoms more efficiently, which stabilizes the key intermediates for the ORR and decreases the activation barrier. This work provides an informative and convenient way for characterizing nitrogen-containing groups on carbon materials, especially in quantifying the active pyridinic nitrogen sites for the ORR.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"64 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142840946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-17DOI: 10.1021/acscatal.4c05268
Charitomeni Angeli, Sara Atienza-Sanz, Simon Schröder, Annika Hein, Yongxin Li, Alexander Argyrou, Angelina Osipyan, Henrik Terholsen, Sandy Schmidt
The biological formation of nitrogen–nitrogen (N–N) bonds represents intriguing reactions that have attracted much attention in the past decade. This interest has led to an increasing number of N–N bond-containing natural products (NPs) and related enzymes that catalyze their formation (referred to in this review as NNzymes) being elucidated and studied in greater detail. While more detailed information on the biosynthesis of N–N bond-containing NPs, which has only become available in recent years, provides an unprecedented source of biosynthetic enzymes, their potential for biocatalytic applications has been minimally explored. With this review, we aim not only to provide a comprehensive overview of both characterized NNzymes and hypothetical biocatalysts with putative N–N bond forming activity, but also to highlight the potential of NNzymes from a biocatalytic perspective. We also present and compare conventional synthetic approaches to linear and cyclic hydrazines, hydrazides, diazo- and nitroso-groups, triazenes, and triazoles to allow comparison with enzymatic routes via NNzymes to these N–N bond-containing functional groups. Moreover, the biosynthetic pathways as well as the diversity and reaction mechanisms of NNzymes are presented according to the direct functional groups currently accessible to these enzymes.
{"title":"Recent Developments and Challenges in the Enzymatic Formation of Nitrogen–Nitrogen Bonds","authors":"Charitomeni Angeli, Sara Atienza-Sanz, Simon Schröder, Annika Hein, Yongxin Li, Alexander Argyrou, Angelina Osipyan, Henrik Terholsen, Sandy Schmidt","doi":"10.1021/acscatal.4c05268","DOIUrl":"https://doi.org/10.1021/acscatal.4c05268","url":null,"abstract":"The biological formation of nitrogen–nitrogen (N–N) bonds represents intriguing reactions that have attracted much attention in the past decade. This interest has led to an increasing number of N–N bond-containing natural products (NPs) and related enzymes that catalyze their formation (referred to in this review as NNzymes) being elucidated and studied in greater detail. While more detailed information on the biosynthesis of N–N bond-containing NPs, which has only become available in recent years, provides an unprecedented source of biosynthetic enzymes, their potential for biocatalytic applications has been minimally explored. With this review, we aim not only to provide a comprehensive overview of both characterized NNzymes and hypothetical biocatalysts with putative N–N bond forming activity, but also to highlight the potential of NNzymes from a biocatalytic perspective. We also present and compare conventional synthetic approaches to linear and cyclic hydrazines, hydrazides, diazo- and nitroso-groups, triazenes, and triazoles to allow comparison with enzymatic routes via NNzymes to these N–N bond-containing functional groups. Moreover, the biosynthetic pathways as well as the diversity and reaction mechanisms of NNzymes are presented according to the direct functional groups currently accessible to these enzymes.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"30 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142840947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-17DOI: 10.1021/acscatal.4c04777
Lu Liu, Liam P. Twight, Shibo Xi, Yingqing Ou, Shannon W. Boettcher
Iron plays a central and critical role in the water oxidation mechanism and the activity of transition-metal oxides and (oxy)hydroxides. Tracking Fe dynamics (deposition/dissolution/electrolyte transport) and unraveling the chemistries of various Fe active sites under oxygen-evolution reaction (OER) conditions are important for catalyst design, particularly for applications in alkaline electrolysis. Here, we use CoOxHy thin films as a platform to investigate Fe transport and reactivity at the catalyst-electrolyte interface and its impact on OER activity. We find that the deposition/dissolution of the surface-absorbed Fe species is governed by the transport of soluble Fe species and applied potential. Soluble Fe species in the electrolyte adsorb on CoOxHy under stirred electrolyte conditions. Accelerated Fe desorption is observed with a more-positive OER potential. The surface-localized Fe sites generated by absorption from soluble Fe species have a higher OER turnover frequency (TOFFe) compared to Fe in codeposited CoFeOxHy films. Operando X-ray absorption spectroscopy shows structural similarity between reference Fe oxyhydroxides and surface Fe sites on CoOxHy, contrasting with Fe sites within the CoOxHy structure made by codeposition, where Fe shows a different apparent X-ray absorption edge energy. The OER activity of the surface-absorbed Fe decreased by Fe desorption but was recoverable by redepositing Fe species under non-OER conditions.
铁在水氧化机制以及过渡金属氧化物和（氧）氢氧化物的活性中发挥着核心和关键作用。跟踪铁的动态（沉积/溶解/电解质迁移）并揭示氧进化反应（OER）条件下各种铁活性位点的化学性质对于催化剂的设计，尤其是碱性电解中的应用非常重要。在此，我们以 CoOxHy 薄膜为平台，研究铁在催化剂-电解质界面上的迁移和反应性及其对 OER 活性的影响。我们发现，表面吸收的铁元素的沉积/溶解受可溶性铁元素的迁移和应用电势的影响。在搅拌电解质条件下，电解质中的可溶性铁会吸附在 CoOxHy 上。随着 OER 电位越来越正，铁的解吸速度也越来越快。与共沉积 CoFeOxHy 薄膜中的铁相比，由可溶性铁吸收产生的表面定位铁位点具有更高的 OER 转换频率 (TOFFe)。运算 X 射线吸收光谱显示，CoOxHy 上的参考铁氧氢氧化物和表面铁位点之间存在结构相似性，这与共沉积 CoOxHy 结构中的铁位点形成鲜明对比，在共沉积 CoOxHy 结构中，铁显示出不同的表观 X 射线吸收边缘能量。表面吸收的铁的 OER 活性因铁的解吸而降低，但在非 OER 条件下通过重新沉积铁物种可以恢复。
{"title":"Dynamics of Fe Adsorption and Desorption from CoOxHy During Oxygen Evolution Reaction Electrocatalysis","authors":"Lu Liu, Liam P. Twight, Shibo Xi, Yingqing Ou, Shannon W. Boettcher","doi":"10.1021/acscatal.4c04777","DOIUrl":"https://doi.org/10.1021/acscatal.4c04777","url":null,"abstract":"Iron plays a central and critical role in the water oxidation mechanism and the activity of transition-metal oxides and (oxy)hydroxides. Tracking Fe dynamics (deposition/dissolution/electrolyte transport) and unraveling the chemistries of various Fe active sites under oxygen-evolution reaction (OER) conditions are important for catalyst design, particularly for applications in alkaline electrolysis. Here, we use CoO<i><sub>x</sub></i>H<i><sub>y</sub></i> thin films as a platform to investigate Fe transport and reactivity at the catalyst-electrolyte interface and its impact on OER activity. We find that the deposition/dissolution of the surface-absorbed Fe species is governed by the transport of soluble Fe species and applied potential. Soluble Fe species in the electrolyte adsorb on CoO<i><sub>x</sub></i>H<i><sub>y</sub></i> under stirred electrolyte conditions. Accelerated Fe desorption is observed with a more-positive OER potential. The surface-localized Fe sites generated by absorption from soluble Fe species have a higher OER turnover frequency (TOF<sub>Fe</sub>) compared to Fe in codeposited CoFeO<i><sub>x</sub></i>H<i><sub>y</sub></i> films. <i>Operando</i> X-ray absorption spectroscopy shows structural similarity between reference Fe oxyhydroxides and surface Fe sites on CoO<i><sub>x</sub></i>H<i><sub>y</sub></i>, contrasting with Fe sites within the CoO<i><sub>x</sub></i>H<i><sub>y</sub></i> structure made by codeposition, where Fe shows a different apparent X-ray absorption edge energy. The OER activity of the surface-absorbed Fe decreased by Fe desorption but was recoverable by redepositing Fe species under non-OER conditions.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"1 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142832583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Exploring visible-light-responsive photocatalysts for photocatalytic lignocellulosic biomass-to-H2 conversion remains a glamorous but challenging goal because the photogenerated holes cannot directly transfer to biomass owing to the absence of a charge transfer channel. Herein, we design ZnIn2S4 nanosheets with abundant sulfur vacancy (VS-ZnIn2S4) as visible light responsive photocatalysts for photocatalytic H2 production from lignocellulosic biomass in the presence of MoS2 as the cocatalyst. In this smartly designed photocatalysts, the sulfur vacancy in ZnIn2S4 reduces the energy barrier of •OH generation reaction and results in the fast dynamics for the generation of •OH, which acts as the crucial species for the oxygenolysis of lignocellulosic biomass. As expected, the H2 generation rate of the optimized MoS2/VS-ZnIn2S4 photocatalyst in α-cellulose and bamboo powder aqueous solution achieves 1572 and 133 μmol·g–1·h–1, respectively. This study validates the feasibility of sulfur vacancy to boost visible light photocatalytic conversion of lignocellulosic biomass into H2 fuel.
{"title":"Sustainable H2 Production from Lignocellulosic Biomass over MoS2 Modified Sulfur Vacancy Enriched ZnIn2S4 Photocatalyst","authors":"Ji-Ping Tang, Yan Chen, Zi-Yi Wang, Yun-Hui Hu, Jia-Hao Wang, Liang Bao, Zong-Yan Zhao, Yong-Jun Yuan","doi":"10.1021/acscatal.4c05707","DOIUrl":"https://doi.org/10.1021/acscatal.4c05707","url":null,"abstract":"Exploring visible-light-responsive photocatalysts for photocatalytic lignocellulosic biomass-to-H<sub>2</sub> conversion remains a glamorous but challenging goal because the photogenerated holes cannot directly transfer to biomass owing to the absence of a charge transfer channel. Herein, we design ZnIn<sub>2</sub>S<sub>4</sub> nanosheets with abundant sulfur vacancy (V<sub>S</sub>-ZnIn<sub>2</sub>S<sub>4</sub>) as visible light responsive photocatalysts for photocatalytic H<sub>2</sub> production from lignocellulosic biomass in the presence of MoS<sub>2</sub> as the cocatalyst. In this smartly designed photocatalysts, the sulfur vacancy in ZnIn<sub>2</sub>S<sub>4</sub> reduces the energy barrier of <sup>•</sup>OH generation reaction and results in the fast dynamics for the generation of <sup>•</sup>OH, which acts as the crucial species for the oxygenolysis of lignocellulosic biomass. As expected, the H<sub>2</sub> generation rate of the optimized MoS<sub>2</sub>/V<sub>S</sub>-ZnIn<sub>2</sub>S<sub>4</sub> photocatalyst in α-cellulose and bamboo powder aqueous solution achieves 1572 and 133 μmol·g<sup>–1</sup>·h<sup>–1</sup>, respectively. This study validates the feasibility of sulfur vacancy to boost visible light photocatalytic conversion of lignocellulosic biomass into H<sub>2</sub> fuel.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"26 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142832585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-16DOI: 10.1021/acscatal.4c05918
Andrés García-Viada, Emma Duro, Celia Sánchez-González, Inés Alonso, Nuria Rodríguez, Javier Adrio, Juan C. Carretero
We herein describe the high-valent cobalt-catalyzed C(sp3)–H functionalization of amide derivatives with silver acetylides generated in situ. The reaction proceeds under kinetic control at 60 °C, with a catalyst loading of 5 mol %. These extraordinarily mild conditions for Co-catalysis enable the synthesis of 5-(Z)-ethylidene pyrrolidin-2-one derivatives in good yield and selectivity. Density functional theory calculations have revealed a unique mechanism involving Co–Ag bimetallic species, rationalizing the nature of the catalytically active species and the role of each additive.
{"title":"Ag/Co-Bimetallic Cooperation in the C–H Functionalization of Aliphatic Amides with Propiolic Acids","authors":"Andrés García-Viada, Emma Duro, Celia Sánchez-González, Inés Alonso, Nuria Rodríguez, Javier Adrio, Juan C. Carretero","doi":"10.1021/acscatal.4c05918","DOIUrl":"https://doi.org/10.1021/acscatal.4c05918","url":null,"abstract":"We herein describe the high-valent cobalt-catalyzed C(sp<sup>3</sup>)–H functionalization of amide derivatives with silver acetylides generated in situ. The reaction proceeds under kinetic control at 60 °C, with a catalyst loading of 5 mol %. These extraordinarily mild conditions for Co-catalysis enable the synthesis of 5-(<i>Z</i>)-ethylidene pyrrolidin-2-one derivatives in good yield and selectivity. Density functional theory calculations have revealed a unique mechanism involving Co–Ag bimetallic species, rationalizing the nature of the catalytically active species and the role of each additive.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"14 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142825608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-16DOI: 10.1021/acscatal.4c04257
Ben Ashley, Chiara Demingo, Henriette Rozeboom, Niccoló Bianciardi, Tomás Dunleavy, Jacob-Jan Haaksma, Yiming Guo, Marco W. Fraaije
Aryl ethers are ubiquitous protecting groups of alcohols and amines in organic chemistry. This is owed to the simplicity of their appendage to molecules and the robust protection afforded. However, aryl ethers and amines can be challenging to cleave, often requiring harsh and unselective reductive conditions. We report the structure-based engineering of a promiscuous, ether-cleaving vanillyl alcohol oxidase-type biocatalyst for activity on a wide range of para-hydroxy benzyl ethers. Two superior quadruple mutants are identified with improved kinetics and substrate scope. One evolved variant and two predecessors are crystallized, and their structures resolved to 2.8–1.5 Å, revealing a significant increase in the volume and flexibility of the active site cavity. To illustrate the potential usefulness of the engineered biocatalysts, one is later coupled with another biocatalyst in a cascade reaction to catalyze the selective cleavage of an uncommon aryl ether protecting group, para-acyloxy benzyl ethers, in good yield and under mild conditions.
{"title":"Biocatalytic Cleavage of para-Acetoxy Benzyl Ethers: Application to Protecting Group Chemistry","authors":"Ben Ashley, Chiara Demingo, Henriette Rozeboom, Niccoló Bianciardi, Tomás Dunleavy, Jacob-Jan Haaksma, Yiming Guo, Marco W. Fraaije","doi":"10.1021/acscatal.4c04257","DOIUrl":"https://doi.org/10.1021/acscatal.4c04257","url":null,"abstract":"Aryl ethers are ubiquitous protecting groups of alcohols and amines in organic chemistry. This is owed to the simplicity of their appendage to molecules and the robust protection afforded. However, aryl ethers and amines can be challenging to cleave, often requiring harsh and unselective reductive conditions. We report the structure-based engineering of a promiscuous, ether-cleaving vanillyl alcohol oxidase-type biocatalyst for activity on a wide range of <i>para</i>-hydroxy benzyl ethers. Two superior quadruple mutants are identified with improved kinetics and substrate scope. One evolved variant and two predecessors are crystallized, and their structures resolved to 2.8–1.5 Å, revealing a significant increase in the volume and flexibility of the active site cavity. To illustrate the potential usefulness of the engineered biocatalysts, one is later coupled with another biocatalyst in a cascade reaction to catalyze the selective cleavage of an uncommon aryl ether protecting group, <i>para</i>-acyloxy benzyl ethers, in good yield and under mild conditions.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"46 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142825753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-16DOI: 10.1021/acscatal.4c04935
Ewald P. J. Jongkind, Jack Domenech, Arthur Govers, Marcel van den Broek, Jean-Marc Daran, Gideon Grogan, Caroline E. Paul
Reductive amination is one of the most synthetically direct routes to access chiral amines. Several Imine Reductases (IREDs) have been discovered to catalyze reductive amination (Reductive Aminases or RedAms), yet they are dependent on the expensive phosphorylated nicotinamide adenine dinucleotide cofactor NADPH and usually more active at basic pH. Here, we describe the discovery and synthetic potential of an IRED from Rhodococcus erythropolis (RytRedAm) that catalyzes reductive amination between a series of medium to large carbonyl and amine compounds with conversions of up to >99% and 99% enantiomeric excess at neutral pH. RytRedAm catalyzes the formation of a substituted γ-lactam and N-methyl-1-phenylethanamine with stereochemistry opposite to that of fungal RedAms, giving the (S)-enantiomer. This enzyme remarkably uses both NADPH and NADH cofactors with KM values of 15 and 247 μM and turnover numbers kcat of 3.6 and 9.0 s–1, respectively, for the reductive amination of hexanal with allylamine. The crystal structure obtained provides insights into the flexibility to also accept NADH, with residues R35 and I69 diverging from that of other IREDs/RedAms in the otherwise conserved Rossmann fold. RytRedAm thus represents a subfamily of enzymes that enable synthetic applications using NADH-dependent reductive amination to access complementary chiral amine products.
{"title":"Discovery and Synthetic Applications of a NAD(P)H-Dependent Reductive Aminase from Rhodococcus erythropolis","authors":"Ewald P. J. Jongkind, Jack Domenech, Arthur Govers, Marcel van den Broek, Jean-Marc Daran, Gideon Grogan, Caroline E. Paul","doi":"10.1021/acscatal.4c04935","DOIUrl":"https://doi.org/10.1021/acscatal.4c04935","url":null,"abstract":"Reductive amination is one of the most synthetically direct routes to access chiral amines. Several Imine Reductases (IREDs) have been discovered to catalyze reductive amination (Reductive Aminases or RedAms), yet they are dependent on the expensive phosphorylated nicotinamide adenine dinucleotide cofactor NADPH and usually more active at basic pH. Here, we describe the discovery and synthetic potential of an IRED from <i>Rhodococcus erythropolis</i> (<i>Ryt</i>RedAm) that catalyzes reductive amination between a series of medium to large carbonyl and amine compounds with conversions of up to >99% and 99% enantiomeric excess at neutral pH. <i>Ryt</i>RedAm catalyzes the formation of a substituted γ-lactam and <i>N</i>-methyl-1-phenylethanamine with stereochemistry opposite to that of fungal RedAms, giving the (<i>S</i>)-enantiomer. This enzyme remarkably uses both NADPH and NADH cofactors with <i>K</i><sub>M</sub> values of 15 and 247 μM and turnover numbers <i>k</i><sub>cat</sub> of 3.6 and 9.0 s<sup>–1</sup>, respectively, for the reductive amination of hexanal with allylamine. The crystal structure obtained provides insights into the flexibility to also accept NADH, with residues R35 and I69 diverging from that of other IREDs/RedAms in the otherwise conserved Rossmann fold. <i>Ryt</i>RedAm thus represents a subfamily of enzymes that enable synthetic applications using NADH-dependent reductive amination to access complementary chiral amine products.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"52 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142832587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-16DOI: 10.1021/acscatal.4c05269
Xianxian Xie, Valentín Briega-Martos, Pere Alemany, Athira Lekshmi Mohandas Sandhya, Tomáš Skála, Miquel Gamón Rodríguez, Jaroslava Nováková, Milan Dopita, Michael Vorochta, Albert Bruix, Serhiy Cherevko, Konstantin M. Neyman, Iva Matolínová, Ivan Khalakhan
Achieving the optimal balance between cost-efficiency and stability of oxygen reduction reaction (ORR) catalysts is currently among the key research focuses aiming at reaching a broader implementation of proton-exchange membrane fuel cells (PEMFCs). To address this challenge, we combine two well-established strategies to enhance both activity and stability of platinum-based ORR catalysts. Specifically, we prepare ternary PtNi–Au alloys, where each alloying element plays a distinct role: Ni reduces costs and boosts ORR activity, while Au enhances stability. A systematic comparative analysis of the activity–stability relationship for compositionally tuned PtNi–Au model layers, prepared by magnetron co-sputtering, was conducted using a diverse range of complementary characterization techniques and electrochemistry, supported by density functional theory calculations. Our study reveals that a progressive increase of the Au concentration in the Pt50Ni50 alloy from 3 to 15 at % leads to opposing catalyst activity and stability trends. Specifically, we observe a decrease in the ORR activity accompanied by an increase in catalyst stability, manifested in the suppression of both Pt and Ni dissolution. Despite the reduced activity compared to PtNi, the PtNi–Au alloy with 15 at % Au still exhibits nearly three times the activity of monometallic Pt. It also demonstrates a significantly improved dissolution stability relative to that of the PtNi alloy and even monometallic Pt. These findings provide valuable insights into the intricate balance between activity and stability in multimetallic ORR catalysts, paving the way for the design of cost-effective and durable materials for PEMFCs.
{"title":"Balancing Activity and Stability through Compositional Engineering of Ternary PtNi–Au Alloy ORR Catalysts","authors":"Xianxian Xie, Valentín Briega-Martos, Pere Alemany, Athira Lekshmi Mohandas Sandhya, Tomáš Skála, Miquel Gamón Rodríguez, Jaroslava Nováková, Milan Dopita, Michael Vorochta, Albert Bruix, Serhiy Cherevko, Konstantin M. Neyman, Iva Matolínová, Ivan Khalakhan","doi":"10.1021/acscatal.4c05269","DOIUrl":"https://doi.org/10.1021/acscatal.4c05269","url":null,"abstract":"Achieving the optimal balance between cost-efficiency and stability of oxygen reduction reaction (ORR) catalysts is currently among the key research focuses aiming at reaching a broader implementation of proton-exchange membrane fuel cells (PEMFCs). To address this challenge, we combine two well-established strategies to enhance both activity and stability of platinum-based ORR catalysts. Specifically, we prepare ternary PtNi–Au alloys, where each alloying element plays a distinct role: Ni reduces costs and boosts ORR activity, while Au enhances stability. A systematic comparative analysis of the activity–stability relationship for compositionally tuned PtNi–Au model layers, prepared by magnetron co-sputtering, was conducted using a diverse range of complementary characterization techniques and electrochemistry, supported by density functional theory calculations. Our study reveals that a progressive increase of the Au concentration in the Pt<sub>50</sub>Ni<sub>50</sub> alloy from 3 to 15 at % leads to opposing catalyst activity and stability trends. Specifically, we observe a decrease in the ORR activity accompanied by an increase in catalyst stability, manifested in the suppression of both Pt and Ni dissolution. Despite the reduced activity compared to PtNi, the PtNi–Au alloy with 15 at % Au still exhibits nearly three times the activity of monometallic Pt. It also demonstrates a significantly improved dissolution stability relative to that of the PtNi alloy and even monometallic Pt. These findings provide valuable insights into the intricate balance between activity and stability in multimetallic ORR catalysts, paving the way for the design of cost-effective and durable materials for PEMFCs.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":"12 1","pages":""},"PeriodicalIF":12.9,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142832588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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