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Molecules (Basel, Switzerland) Oct 2023A series of phosphorus and selenium -substituted acenaphthene species with the phosphino group oxidized by O, S, and Se has been isolated and fully characterized,...
A series of phosphorus and selenium -substituted acenaphthene species with the phosphino group oxidized by O, S, and Se has been isolated and fully characterized, including by single-crystal X-ray diffraction. The P(V) and Se(II) systems showed fluxional behavior in solution due to the presence of two major rotamers, as evidenced with solution NMR spectroscopy. Using Variable-Temperature NMR (VT NMR) and supported by DFT (Density Functional Theory) calculations and solid-state NMR, the major rotamers in the solid and in solution were identified. All compounds showed a loss of the through-space coupling observed in the unoxidized P(III) and Se(II) systems due to the sequestration of the lone pair of the phosphine, which has been previously identified as the major contributor to the coupling pathway.
PubMed: 37959719
DOI: 10.3390/molecules28217297 -
ACS Organic & Inorganic Au Aug 2023Monodentate phosphine-ligated nickel compounds, , [Ni(PPh)] are relevant as active catalysts across a broad range of reactions. This report expands upon the coordination...
Monodentate phosphine-ligated nickel compounds, , [Ni(PPh)] are relevant as active catalysts across a broad range of reactions. This report expands upon the coordination chemistry of this family, offering the reactivity of allyl- and vinyl-substituted diphenylphosphine (PPhR) with [Ni(COD)] (COD = 1,5-cyclooctadiene). These reactions provide three-coordinate dinickelacycles that are intermolecularly tethered through adjacent {Ni}-olefin interactions. The ring conformation of such cycles has been studied in the solid-state and using theoretical calculations. Here, a difference in reaction outcome is linked to the presence of an allyl vs vinyl group, where the former is observed to undergo rearrangement, bringing about challenges in clean product isolation.
PubMed: 37545661
DOI: 10.1021/acsorginorgau.3c00010 -
Organic Letters Apr 2024In this Letter, we report a direct and robust desulfurization method employing water-soluble phosphine, specifically tris(2-carboxyethyl)phosphine hydrochloride (TCEP),...
In this Letter, we report a direct and robust desulfurization method employing water-soluble phosphine, specifically tris(2-carboxyethyl)phosphine hydrochloride (TCEP), and tetrahydroxydiboron (B(OH)), which serves as a radical initiator. This innovative reaction exhibits compatibility with a diverse array of substrates, including cysteine residues in chemically synthesized oligopeptides and cyclic peptides, alkyl thiols in bioactive molecules, disulfides in commercial proteins, and selenocysteine. We optimized the reaction conditions to minimize the formation of undesired oxidized and borylated byproducts. Furthermore, the refined desulfurization process is executed after native chemical ligation (NCL) in a single pot, streamlining the existing synthetic approaches. This demonstrates its potential applications in the synthesis of complex peptides and proteins, showcasing a significant advancement in the field.
Topics: Indicators and Reagents; Peptides; Proteins; Cysteine; Sulfhydryl Compounds
PubMed: 38517348
DOI: 10.1021/acs.orglett.4c00609 -
Journal of the American Chemical Society Oct 2023We introduce a direct conversion of alkyl thiols into boronic acids, facilitated by a water-soluble phosphine, 1,3,5-triaza-7-phosphaadamantane (PTA), in conjunction...
We introduce a direct conversion of alkyl thiols into boronic acids, facilitated by a water-soluble phosphine, 1,3,5-triaza-7-phosphaadamantane (PTA), in conjunction with tetrahydroxydiboron (B(OH)), acting as both a radical initiator and a boron source. This desulfurative borylation reaction has been successfully applied to various substrates, including cysteine residues in oligopeptides and small proteins, primary alkyl thiols found in pharmaceutical compounds, disulfides, and selenocysteine. Optimization of reaction conditions was undertaken to reduce the formation of unwanted reactions, such as the reduction of alanyl or other primary radicals, and to prevent deleterious reactions between the phosphine and N-terminal amine that lead to methylene adducts by utilizing a buffer containing glycine-glycine (GG) dipeptide. The developed method is characterized by its operational simplicity and robustness. Moreover, its compatibility with various functional groups present in peptides and proteins makes it a promising tool for late-stage functionalization, extending its potential application across a broad spectrum of chemical and biological targets.
Topics: Proteins; Peptides; Sulfhydryl Compounds; Glycine
PubMed: 37812507
DOI: 10.1021/jacs.3c09081 -
Angewandte Chemie (International Ed. in... Jan 2024Allenoates are versatile building blocks which are primarily activated and controlled using chiral tert. phosphine and tert. amine Lewis bases. We herein report the...
Allenoates are versatile building blocks which are primarily activated and controlled using chiral tert. phosphine and tert. amine Lewis bases. We herein report the first example of allenoate activation by using chiral isochalcogenoureas (IChU) for formal (4+2) cycloaddition reactions. Compared to established phosphine and amine catalysis, the use of these easily available Lewis bases enables new stereoselective reaction pathways proceeding with high enantioselectivities, diastereoselectivities, and in good yields. In addition, the factors governing enantioselectivity and the origin of the observed differences compared to other commonly used Lewis bases are explained.
PubMed: 38010747
DOI: 10.1002/anie.202315345 -
Accounts of Chemical Research Nov 2023ConspectusThe activation and functionalization of N to form nitrogen-element bonds have long posed challenges to industrial, biological, and synthetic chemists. The...
ConspectusThe activation and functionalization of N to form nitrogen-element bonds have long posed challenges to industrial, biological, and synthetic chemists. The first transition-metal dinitrogen complex prepared by Allen and Senoff in 1965 provoked researchers to explore homogeneous N fixation. Despite intensive research in the last six decades, efficient and quantitative conversion of N to diazenido and hydrazido species remains problematic. Relative to a plethora of reactions to generate N complexes, their functionalization reactions are rather rare, and the yields are often unsatisfactory, emphasizing the need for systematic investigations of the reaction mechanisms.In this Account, we summarize our recent work on the synthesis, spectroscopic features, electronic structures, and reactivities of several Cr-N complexes. Initially, a series of dinuclear and trinuclear Cr(I)-N complexes bearing cyclopentadienyl-phosphine ligands were accessed. However, they cannot achieve N functionalization but undergo oxidative addition reactions with phenylsilane, azobenzene, and other unsaturated organic compounds at the low-valent Cr(I) centers rather than at the N unit. Further reduction of these Cr(I) complexes leads to the formation of more activated mononuclear Cr(0) bis-dinitrogen complexes. Remarkably, silylation of the cyclopentadienyl-phosphine Cr(0)-N complex with MeSiCl afforded the first Cr hydrazido complex. This process follows the distal pathway to functionalize the N atom twice, yielding an end-on η-hydrazido complex, Cr(III)═N-N(SiMe). In contrast, upon substitution of the phosphine ligand in the Cr(0)-N complex with a N-heterocyclic carbene (NHC) ligand, the corresponding reaction with MeSiCl proceeds via the alternating pathway; the silylation occurs at both N and N atoms and generates a side-on η-hydrazido complex, Cr(III)(η-MeSiN-NSiMe). Both silylation reactions are inevitably accompanied by the formation of Cr(III) hydrazido complexes and Cr(II) chlorides with a 2:1 ratio. These processes exhibit a peculiar '3-4-2-1' stoichiometry (i.e., treating 3 equiv of Cr(0)-N complexes with 4 equiv of MeSiCl yields 2 equiv of Cr(III) disilyl-hydrazido complexes and 1 equiv of Cr(II) chloride). Upon replacing the monodentate phosphine and/or NHC ligand with a bisphosphine ligand, a monodinitrogen Cr(0) complex, instead of the bis-dinitrogen Cr(0) complexes, is obtained; consequently, the silylation reactions progress via the normal two-electron route, which passes through Cr(II)-N═N-R diazenido species as an intermediate and furnishes [Cr(IV)═N-NR] hydrazido as the final products. More importantly, this type of Cr(0)-N complex can be not only silylated but also protonated and alkylated proficiently. All of the second-order reaction rates of the first and second transformations are determined along with the lifetimes of the intervening diazenido species. Based on these findings, we have successfully carried out nearly quantitative preparations of the Cr(IV) hydrazido species with unmixed or hybrid substituents.The studies of Cr-N systems provide effective approaches for the activation and functionalization of N, deepening the understanding of N electrophilic attack. We hope that this Account will inspire more discoveries related to the transformation of gaseous N to high-value-added nitrogen-containing organic compounds.
PubMed: 37937752
DOI: 10.1021/acs.accounts.3c00476 -
Inorganic Chemistry Feb 2024Key strategies in cluster synthesis include the use of modulating agents (e.g., coordinating additives). We studied the influence of various phosphines exhibiting...
Key strategies in cluster synthesis include the use of modulating agents (e.g., coordinating additives). We studied the influence of various phosphines exhibiting different steric and electronic properties on the reduction of the Au(I) precursor to Au(0) clusters. We report a synthesis of the bimetallic clusters [Au(AlCp*)] = [AuAl](Cp*) () and [HAu(AlCp*)] = [HAuAl](Cp*) () (Cp* = pentamethylcyclopentadiene) using Au(I) precursors and AlCp*. The cluster [Au(AlCp*)] = [AuAl](Cp*) () was isolated and identified as an intermediate species in the reactions to and . The processes of cluster growth and degradation were investigated by in situ H NMR and LIFDI-MS techniques. The structures of and were established by DFT geometry optimization. These octahedral clusters can both be described as closed-shell 18-electron superatoms.
PubMed: 38335041
DOI: 10.1021/acs.inorgchem.3c03790 -
Organic Chemistry Frontiers : An... Nov 2023The development of methods for replication of synthetic information oligomers will underpin the use of directed evolution to search new chemical space. Template-directed...
The development of methods for replication of synthetic information oligomers will underpin the use of directed evolution to search new chemical space. Template-directed replication of triazole oligomers has been achieved using a covalent primer in conjunction with non-covalent binding of complementary building blocks. A phenol primer equipped with an alkyne was first attached to a benzoic recognition unit on a mixed sequence template selective covalent ester base-pair formation. The remaining phenol recognition units on the template were then used for non-covalent binding of phosphine oxide oligomers equipped with an azide. The efficiency of the templated CuAAC reaction between the primer and phosphine oxide building blocks was investigated as a function of the number of H-bonds formed with the template. Increasing the strength of the non-covalent interaction between the template and the azide lead to a significant acceleration of the templated reaction. For shorter phosphine oxide oligomers intermolecular reactions compete with the templated process, but quantitative templated primer elongation was achieved with a phosphine oxide 3-mer building block that was able to form three H-bonds with the template. NMR spectroscopy and molecular models suggest that the template can fold, but addition of the phosphine oxide 3-mer leads to a complex with three H-bonds between phosphine oxide and phenol groups, aligning the azide and alkyne groups in a favourable geometry for the CuAAC reaction. In the product duplex, H and P NMR data confirm the presence of the three H-bonded base-pairs, demonstrating that the covalent and non-covalent base-pairs are geometrically compatible. A complete replication cycle was carried out starting from the oligotriazole template by covalent attachment of the primer, followed by template-directed elongation, and hydrolysis of the the ester base-pair in the resulting duplex to regenerate the template and liberate the copy strand. We have previously demonstrated sequence-selective oligomer replication using covalent base-pairing, but the trimer building block approach described here is suitable for replication of sequence information using non-covalent binding of the monomer building blocks to a template.
PubMed: 38022796
DOI: 10.1039/d3qo01717f -
Respiratory Research Jan 2024This study aimed to investigate the interactions among three core elements of respiratory infection-pathogen, lung microbiome, and host response-and their avocation with...
BACKGROUND
This study aimed to investigate the interactions among three core elements of respiratory infection-pathogen, lung microbiome, and host response-and their avocation with the severity and outcomes of Mycoplasma pneumoniae pneumonia (MPP) in children.
METHODS
We prospectively collected bronchoalveolar lavage fluid from a cohort of 41 children with MPP, including general MPP (GMPP) and complicated MPP (CMPP), followed by microbiome and transcriptomic analyses to characterize the association among pathogen, lung microbiome, and host response and correlate it with the clinical features and outcomes.
RESULTS
The lung microbiome of patients with CMPP had an increased relative abundance of Mycoplasma pneumoniae (MP) and reduced alpha diversity, with 76 differentially expressed species. Host gene analysis revealed a key module associated with neutrophil function and several inflammatory response pathways. Patients with a high relative abundance of MP, manifested by a specific lung microbiome and host response type, were more prone to CMPP and had a long imaging recovery time.
CONCLUSION
Patients with CMPP have a more disrupted lung microbiome than those with GMPP. MP, lung microbiome, and host response interacts with each other and are closely related to disease severity and outcomes in children with MPP.
Topics: Child; Humans; Mycoplasma pneumoniae; Transcriptome; Pneumonia, Mycoplasma; Lung; Nitrobenzenes; Organophosphorus Compounds
PubMed: 38238712
DOI: 10.1186/s12931-024-02687-4 -
Polymers Oct 2023A new set of microporous organic polymers (POPs) containing diphosphine derivatives synthesized by knitting via Friedel-Crafts has been attained. These amorphous...
A new set of microporous organic polymers (POPs) containing diphosphine derivatives synthesized by knitting via Friedel-Crafts has been attained. These amorphous three-dimensional materials have been prepared by utilizing diphosphines, 1,3,5-triphenylbenzene, and biphenyl as nucleophile aromatic groups, dimethoxymethane as the electrophilic linker, and FeCl as a promoting catalyst. These polymer networks display moderate thermal stability and high microporosity, boasting BET surface areas above 760 m/g. They are capable of coordinating with palladium acetate, using the phosphine derivative as an anchoring center, and have proven to be highly efficient catalysts in Suzuki-Miyaura coupling reactions involving bromo- and chloroarenes under environmentally friendly (using water and ethanol as solvents) and aerobic conditions. These supported catalysts have achieved excellent turnover numbers (TON) and turnover frequencies (TOF), while maintaining good recyclability without significant loss of activity or Pd leaching after five consecutive reaction cycles.
PubMed: 37896387
DOI: 10.3390/polym15204143