Repurposing Iron‐ and 2‐Oxoglutarate‐Dependent Oxygenases to Catalyze Olefin HydrationWang, Bingnan; Lu, Yong; Cha, Lide; Chen, Tzu‐Yu; Palacios, Philip M.; Li, Liping; Guo, Yisong; Chang, Wei‐chen; Chen, Chuo
doi: 10.1002/anie.202311099pmid: 37639670
Mononuclear nonheme iron(II) and 2‐oxoglutarate (Fe/2OG)‐dependent oxygenases and halogenases are known to catalyze a diverse set of oxidative reactions, including hydroxylation, halogenation, epoxidation, and desaturation in primary metabolism and natural product maturation. However, their use in abiotic transformations has mainly been limited to C−H oxidation. Herein, we show that various enzymes of this family, when reconstituted with Fe(II) or Fe(III), can catalyze Mukaiyama hydration—a redox neutral transformation. Distinct from the native reactions of the Fe/2OG enzymes, wherein oxygen atom transfer (OAT) catalyzed by an iron‐oxo species is involved, this nonnative transformation proceeds through a hydrogen atom transfer (HAT) pathway in a 2OG‐independent manner. Additionally, in contrast to conventional inorganic catalysts, wherein a dinuclear iron species is responsible for HAT, the Fe/2OG enzymes exploit a mononuclear iron center to support this reaction. Collectively, our work demonstrates that Fe/2OG enzymes have utility in catalysis beyond the current scope of catalytic oxidation.
Postsynthetic Photochemical Modification and 2D Structuring of Zr‐MOF Thin Films Containing Benzophenone Linker MoleculesHindricks, Karen D. J.; Schaate, Andreas; Behrens, Peter
doi: 10.1002/anie.202303753pmid: 37154383
For the fabrication of next‐generation MOF‐based devices the availability of highly adaptable materials in suitable shapes is crucial. Here, we present thin films of a metal–organic framework (MOF) containing photoreactive benzophenone units. Crystalline, oriented and porous films of the zirconium‐based bzpdc‐MOF (bzpdc=benzophenone‐4‐4′‐dicarboxylate) are prepared by direct growth on silicon or glass substrates. Via a subsequent photochemical modification of the Zr‐bzpdc‐MOF films, various properties can be tuned postsynthetically by covalent attachment of modifying agents. Apart from the modification with small molecules, also grafting‐from polymerization reactions are possible. In a further extension, 2D structuring and photo‐writing of defined structures is also possible, for example by using a photolithographic approach, paving the way towards micro‐patterned MOF surfaces.
Macrocyclic β‐Sheets Stabilized by Hydrogen Bond SurrogatesNazzaro, Alex; Lu, Brandon; Sawyer, Nicholas; Watkins, Andrew M.; Arora, Paramjit S.
doi: 10.1002/anie.202303943pmid: 37170337
Mimics of protein secondary and tertiary structure offer rationally‐designed inhibitors of biomolecular interactions. β‐Sheet mimics have a storied history in bioorganic chemistry and are typically designed with synthetic or natural turn segments. We hypothesized that replacement of terminal inter‐β‐strand hydrogen bonds with hydrogen bond surrogates (HBS) may lead to conformationally‐defined macrocyclic β‐sheets without the requirement for natural or synthetic β‐turns, thereby providing a minimal mimic of a protein β‐sheet. To access turn‐less antiparallel β‐sheet mimics, we developed a facile solid phase synthesis protocol. We surveyed a dataset of protein β‐sheets for naturally observed interstrand side chain interactions. This bioinformatics survey highlighted an over‐abundance of aromatic–aromatic, cation‐π and ionic interactions in β‐sheets. In correspondence with natural β‐sheets, we find that minimal HBS mimics show robust β‐sheet formation when specific amino acid residue pairings are incorporated. In isolated β‐sheets, aromatic interactions endow superior conformational stability over ionic or cation‐π interactions. Circular dichroism and NMR spectroscopies, along with high‐resolution X‐ray crystallography, support our design principles.
Metal Free Dötz‐Type Aminobenzannulation Reaction via 1,1‐Dipoles Cross‐CouplingCai, Wei; Huang, You
doi: 10.1002/anie.202310133pmid: 37610557
Aryl amines are of constant interest in organic synthesis owing to their ubiquity in natural products, pharmaceuticals, and organic materials. However, C−H amination or pre‐functionalization frequently results in uncontrollable site selectivity, over activation and the generation of inseparable mixtures of regio‐isomers. Here we present a novel metal free Dötz‐type aminobenzannulation reaction that circumvents the selectivity issues inherent in aromatic chemistry, as well as the use of stoichiometric unstable organolithium reagents and toxic chromium complexes. The concept of utilizing readily available isocyanides and Morita–Baylis–Hillman (MBH) carbonates to achieve 1,1‐dipoles cross‐coupling to construct ketenimine is the key to success, which has been experimentally and computationally verified. The tandem 6π‐electrocyclization/aromatization process offers a versatile method for synthesizing functionalized anilines, fused aryl amines and fused heteroaryl amines.
Hollow STW‐Type Zeolite Single Crystals with Aluminum Gradient for Highly Selective Production of p‐Xylene from Methanol‐Toluene AlkylationJiao, Feng; Yu, Pengyao; Cui, Yuchen; Li, Hao; Hu, Qing; Xu, Yanan; Mintova, Svetlana; Guo, Hailing; Du, Hongbin
doi: 10.1002/anie.202310419pmid: 37615859
Zeolites with uniform micropores are important shape‐selective catalysts. However, the external acid sites of zeolites have a negative impact on shape‐selective catalysis, and the microporosity may lead to serious diffusion limitation. Herein, we report on the direct synthesis of hierarchical hollow STW‐type zeolite single crystals with a siliceous exterior. In an alkalinous fluoride medium, the nucleation of highly siliceous STW zeolites takes place first, and the nanocrystals are preferentially aligned on the outer surface of the gel agglomerates to grow into single crystalline shells upon crystallization. The lagged crystallization of the internal Al‐rich amorphous gels onto the inner surface of nanocrystalline zeolite shells leads to the formation of hollow cavities in the core of the zeolite crystals. The hollow zeolite single crystals possess a low‐to‐high aluminum gradient from the surface to the core, resulting in an intrinsic inert external surface, and exhibit superior catalytic performance in toluene methylation reactions.
Synthetic Heparanase Inhibitors Can Prevent Herpes Simplex Viral SpreadChopra, Pradeep; Yadavalli, Tejabhiram; Palmieri, Francesco; Jongkees, Seino A. K.; Unione, Luca; Shukla, Deepak; Boons, Geert‐Jan
doi: 10.1002/anie.202309838pmid: 37555536
Herpes simplex virus (HSV‐1) employs heparan sulfate (HS) as receptor for cell attachment and entry. During late‐stage infection, the virus induces the upregulation of human heparanase (Hpse) to remove cell surface HS allowing viral spread. We hypothesized that inhibition of Hpse will prevent viral release thereby representing a new therapeutic strategy for HSV‐1. A range of HS‐oligosaccharides was prepared to examine the importance of chain length and 2‐O‐sulfation of iduronic moieties for Hpse inhibition. It was found that hexa‐ and octasaccharides potently inhibited the enzyme and that 2‐O‐sulfation of iduronic acid is tolerated. Computational studies provided a rationale for the observed structure–activity relationship. Treatment of human corneal epithelial cells (HCEs) infected with HSV‐1 with the hexa‐ and octasaccharide blocked viral induced shedding of HS which significantly reduced spread of virions. The compounds also inhibited migration and proliferation of immortalized HCEs thereby providing additional therapeutic properties.
A Bio‐Inspired Trehalose Additive for Reversible Zinc Anodes with Improved Stability and KineticsLi, Haoyu; Ren, Yu; Zhu, Yue; Tian, Jiaming; Sun, Xinyi; Sheng, Chuanchao; He, Ping; Guo, Shaohua; Zhou, Haoshen
doi: 10.1002/anie.202310143pmid: 37578683
The moderate reversibility of Zn anodes, as a long‐standing challenge in aqueous zinc‐ion batteries, promotes the exploration of suitable electrolyte additives continuously. It is crucial to establish the absolute predominance of smooth deposition within multiple interfacial reactions for stable zinc anodes, including suppressing side parasitic reactions and facilitating Zn plating process. Trehalose catches our attention due to the reported mechanisms in sustaining biological stabilization. In this work, the inter‐disciplinary application of trehalose is reported in the electrolyte modification for the first time. The pivotal roles of trehalose in suppressed hydrogen evolution and accelerated Zn deposition have been investigated based on the principles of thermodynamics as well as reaction kinetics. The electrodeposit changes from random accumulation of flakes to dense bulk with (002)‐plane exposure due to the unlocked crystal‐face oriented deposition with trehalose addition. As a result, the highly reversible Zn anode is obtained, exhibiting a high average CE of 99.8 % in the Zn/Cu cell and stable cycling over 1500 h under 9.0 % depth of discharge in the Zn symmetric cell. The designing principles and mechanism analysis in this study could serve as a source of inspiration in exploring novel additives for advanced Zn anodes.