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Journal of the American Chemical Society Dec 2018The nickel-catalyzed synthesis of tetrasubstituted cyclobutenes from alkynes is reported. This transformation is uniquely promoted by the use of a primary...
The nickel-catalyzed synthesis of tetrasubstituted cyclobutenes from alkynes is reported. This transformation is uniquely promoted by the use of a primary aminophosphine, an unusual ligand in nickel catalysis. Mechanistic insights for this new transformation are provided, and postreaction modifications of the cyclobutene products to stereodefined cyclic and acyclic compounds are reported, including the synthesis of epi-truxillic acid.
Topics: Alkynes; Catalysis; Cycloaddition Reaction; Cyclobutanes; Ligands; Models, Chemical; Nickel; Oxidation-Reduction; Phosphines
PubMed: 30517785
DOI: 10.1021/jacs.8b09677 -
Journal of the American Chemical Society Apr 2018Protein lysine crotonylation has emerged as an important post-translational modification (PTM) in the regulation of gene transcription through epigenetic mechanisms....
Protein lysine crotonylation has emerged as an important post-translational modification (PTM) in the regulation of gene transcription through epigenetic mechanisms. Here we introduce a chemical probe, based on a water-soluble phosphine warhead, which reacts with the crotonyl modification. We show that this reagent is complementary to antibody-based tools allowing detection of endogenous cellular proteins such as histones carrying the crotonylation PTM. The tool is also used to show that the histone acylation activity of the transcriptional coactivator, p300, can be activated by pre-existing lysine crotonylation through a positive feedback mechanism. This reagent provides a versatile and sensitive probe for the analysis of this PTM.
Topics: E1A-Associated p300 Protein; Histones; Humans; Lysine; Molecular Probes; Phosphines; Protein Processing, Post-Translational
PubMed: 29584949
DOI: 10.1021/jacs.7b13141 -
International Maritime Health 2020During ship transport of organic cargo e.g. soybeans in bulk or textiles in containers, there is a risk of pests damaging the cargo during transport as well as of...
BACKGROUND
During ship transport of organic cargo e.g. soybeans in bulk or textiles in containers, there is a risk of pests damaging the cargo during transport as well as of unwanted global spread of organisms. Consequently, fumigation of the shipped goods is recommended. While aiming to protect the cargo from being damaged by pests during the transport time, fumigation constitutes a risk to the health of seafarers and port workers and even fatal cases are seen. Phosphine gas is increasingly applied for fumigation. Based on former experiences this article aims to describe the risk and to provide recommendations for prevention.
MATERIALS AND METHODS
All reports of acute occupational exposures to phosphine in the maritime shipping industry to the Belgian Poison Centre were analysed and compared to reports in a study by ANSES (Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail), which collected data from the French Poison Centres. Data were registered and analysed between the 1st of January 1999 and the 31 of December 2018.
RESULTS
The reported incidents have so far been rather few but seem to have increased over the last years. Symptoms are gastro-intestinal, neurologic and respiratory and often seem "vague" and non-specific and are often difficult to recognise for first responders. In the cases where the aetiology of the incident is known, there often seems to be a lack of clear information about the risk and options for mitigation in workplaces and among the workers. Twelve publications of case reports were included from the literature review that showed the same patterns as found in the registered incident reports.
CONCLUSIONS
There seems to be an increase in incidents of acute poisoning from phosphine worldwide. This increase could be linked to the phasing out of methyl bromide in the Montreal Protocol but may also have other explanations. Strict precautions are needed when using phosphine for fumigation of ship cargoes and containers. Since symptoms are often vague, first-responders need to pay attention to the possible occurrence of acute phosphine intoxication as it may be life threatening. Phosphine intoxication remains a diagnosis nor to underestimate not to miss. Further monitoring and research is needed. Preventive actions are mandatory. It is essential to implement in a strict way the existing legislation of an in-transit fumigation with phosphine. Training of the crew and good communication between the different actors during an in-transit fumigation (ship-owner, captain, fumigator, crew, longshoremen) is the key of a good prevention of accidents.
Topics: Adult; Belgium; France; Humans; Male; Occupational Diseases; Occupational Exposure; Phosphines; Ships
PubMed: 33001425
DOI: 10.5603/IMH.2020.0028 -
Chemphyschem : a European Journal of... Nov 2022Phosphinylidenes are an important class of organophosphorus compounds that can exhibit tautomerization between tricoordinated P(III) hydroxide (R R POH) and a...
Phosphinylidenes are an important class of organophosphorus compounds that can exhibit tautomerization between tricoordinated P(III) hydroxide (R R POH) and a pentacoordinated P(V) oxide (R R P(O)H) form. Herein we show, using the canonical variational transition state theory combined with multidimensional small-curvature tunneling approximation, the dominance of proton tunneling in the two-water-bridged tautomerizations of phosphinous acid and model phosphinylidenes comprising phosphosphinates, H-phosphonates, H-phosphinates and secondary phosphine oxides. Based on the studied system, the contribution of thermally-activated tunneling is predicted to speed up the semiclassical reaction rate by ca. threefold to as large as two orders of magnitude at 298.15 K in the gas phase. The large KIE and the concavity in the Arrhenius plots are further fingerprints of tunneling. The simulations also predicted that the rapid tunneling rate and short half-life span for the forward reaction, as opposed to the reverse reaction in fluorinated secondary phosphine oxides, would result in P(V) being elusive and only P(III) being isolable, which agrees with previous experiments where only P(III) was detected by IR and NMR spectroscopy. We also explored the role of solvent and predicted tunneling to be substantial.
Topics: Water; Phosphines; Protons; Oxides; Catalysis; Kinetics
PubMed: 35867911
DOI: 10.1002/cphc.202200396 -
Chemical Science Jul 2022Syntheses of Vaska-type complexes [IrPX(CO)] (P = phosphine, X = halide) with all four common halides (fluoride, chloride, bromide, and iodide) was attempted using a...
Syntheses of Vaska-type complexes [IrPX(CO)] (P = phosphine, X = halide) with all four common halides (fluoride, chloride, bromide, and iodide) was attempted using a protic and hemilabile imidazolyl di--butyl phosphine ligand. In the solid-state, all four complexes were found to be ionic with the halides in the outer-sphere, and the fourth coordination site of the square plane occupied by the imidazole arm of the ligand. In solution, however, the chloride complex was found to be in equilibrium with an octahedral Ir-H species at room temperature. For the bromide and iodide analogs, the corresponding Ir-H species were also observed but only after heating the solutions. The neutral Ir Vaska's analogs for X = Cl, Br, and I were obtained upon addition of excess halide salt, albeit heating was required for X = Br and I. The Ir-H species are proposed to originate from tautomerization of minor amounts of the electron rich neutral Vaska analog (halide inner-sphere and phosphines monodentate) that are in equilibrium with the ionic species. Heating is required for the larger anions of bromide and iodide to overcome a kinetic barrier associated with their movement to an inner-sphere position prior to tautormerization. For the fluoride analog, the Ir-H was not observed, attributable to strong hydrogen bonding interactions of the imidazolyl proton with the fluoride anion.
PubMed: 35865898
DOI: 10.1039/d2sc00279e -
Topics in Current Chemistry (Cham) Apr 2017The phosphoryl group, PO, is the dynamic structural unit in the biological chemistry of phosphorus. Its transfer from a donor to an acceptor atom, with oxygen much more... (Review)
Review
The phosphoryl group, PO, is the dynamic structural unit in the biological chemistry of phosphorus. Its transfer from a donor to an acceptor atom, with oxygen much more prevalent than nitrogen, carbon, or sulfur, is at the core of a great majority of enzyme-catalyzed reactions involving phosphate esters, anhydrides, amidates, and phosphorothioates. The serendipitous discovery that the phosphoryl group could be labeled by "nuclear mutation," by substitution of PO by MgF or AlF, has underpinned the application of metal fluoride (MF ) complexes to mimic transition states for enzymatic phosphoryl transfer reactions, with sufficient stability for experimental analysis. Protein crystallography in the solid state and F NMR in solution have enabled direct observation of ternary and quaternary protein complexes embracing MF transition state models with precision. These studies have underpinned a radically new mechanistic approach to enzyme catalysis for a huge range of phosphoryl transfer processes, as varied as kinases, phosphatases, phosphomutases, and phosphohydrolases. The results, without exception, have endorsed trigonal bipyramidal geometry (tbp) for concerted, "in-line" stereochemistry of phosphoryl transfer. QM computations have established the validity of tbp MF complexes as reliable models for true transition states, delivering similar bond lengths, coordination to essential metal ions, and virtually identical hydrogen bond networks. The emergence of protein control of reactant orbital overlap between bond-forming species within enzyme transition states is a new challenging theme for wider exploration.
Topics: Aluminum Compounds; Fluorides; Magnesium Compounds; Molecular Structure; Phosphines; Phosphoric Monoester Hydrolases; Phosphotransferases; Phosphotransferases (Phosphomutases)
PubMed: 28299727
DOI: 10.1007/s41061-017-0130-y -
International Journal of Molecular... Jan 2023The present work describes an efficient reaction of electrochemical phosphorylation of phenylacetylene controlled by the composition of catalytic nanoparticles based on...
The present work describes an efficient reaction of electrochemical phosphorylation of phenylacetylene controlled by the composition of catalytic nanoparticles based on non-noble-metals. The sought-after products are produced via the simple synthetic protocol based on room temperature, atom-economical reactions, and silica nanoparticles (SNs) loaded by one or two d-metal ions as nanocatalysts. The redox and catalytic properties of SNs can be tuned with a range of parameters, such as compositions of the bimetallic systems, their preparation method, and morphology. Monometallic SNs give phosphorylated acetylene with retention of the triple bond, and bimetallic SNs give a bis-phosphorylation product. This is the first example of acetylene and phosphine oxide C-H/P-H coupling with a regenerable and recyclable catalyst.
Topics: Oxides; Metals; Nanoparticles; Alkynes
PubMed: 36614210
DOI: 10.3390/ijms24010765 -
European Journal of Medicinal Chemistry Oct 2020Herein, we review developments in synthesis, structure, and biological (anti-cancer) activities of 1,1-bis(diphenylphosphino)methane (dppm) bridged homo- and... (Review)
Review
Herein, we review developments in synthesis, structure, and biological (anti-cancer) activities of 1,1-bis(diphenylphosphino)methane (dppm) bridged homo- and heterobimetallic systems of the type LM(μ-dppm)M'L (M and M' are transition metals which may be different or the same and L are co-ligands) since the first such reported bimetallic system in 1987 until the present time (2020). As the simplest diphosphine, dppm enables facile formation of bimetallic complexes, where, given the short spacer between the PPh groups, close spatial proximity of the metal centres is ensured. We concentrate on complexes bearing no M-M interaction and contrast biological activities of these complexes with mononuclear counterparts and positive control agents such as cisplatin, in an attempt to elucidate patterns in the biological activities of these complexes.
Topics: Anti-Bacterial Agents; Antineoplastic Agents; Cell Line, Tumor; Cell Survival; Coordination Complexes; Crystallography, X-Ray; Drug Screening Assays, Antitumor; Humans; Ligands; Metals; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Phosphines; Salmonella typhimurium; Spectrophotometry, Ultraviolet; Staphylococcus aureus; Structure-Activity Relationship
PubMed: 32784095
DOI: 10.1016/j.ejmech.2020.112613 -
Angewandte Chemie (International Ed. in... Apr 2021Polyalkyl furans are widespread in nature, often performing important biological roles. Despite a plethora of methods for the synthesis of tetrasubstituted furans, the...
Polyalkyl furans are widespread in nature, often performing important biological roles. Despite a plethora of methods for the synthesis of tetrasubstituted furans, the construction of tetraalkyl furans remains non-trivial. The prevalence of alkyl groups in bioactive furan natural products, combined with the desirable bioactivities of tetraalkyl furans, calls for a general synthetic protocol for polyalkyl furans. This paper describes a Michael-Heck approach, using sequential phosphine-palladium catalysis, for the preparation of various polyalkyl furans from readily available precursors. The versatility of this method is illustrated by the total syntheses of nine distinct polyalkylated furan natural products belonging to different classes, namely the furanoterpenes rosefuran, sesquirosefuran, and mikanifuran; the marine natural products plakorsins A, B, and D and plakorsin D methyl ester; and the furan fatty acids 3D5 and hydromumiamicin.
Topics: Biological Products; Catalysis; Furans; Molecular Structure; Organometallic Compounds; Palladium; Phosphines
PubMed: 33533120
DOI: 10.1002/anie.202015232 -
Molecules (Basel, Switzerland) Apr 2020In an effort to explain the experimentally observed variation of the photocatalytic activity of t Bu 3 P, n Bu 3 P and (MeO) 3 P in the blue-light regime [Helmecke et...
In an effort to explain the experimentally observed variation of the photocatalytic activity of t Bu 3 P, n Bu 3 P and (MeO) 3 P in the blue-light regime [Helmecke et al., Org. Lett. 21 (2019) 7823], we have explored the absorption characteristics of several phosphine- and phosphite-IC 4 F 9 adducts by means of relativistic density functional theory and multireference configuration interaction methods. Based on the results of these computational and complementary experimental studies, we offer an explanation for the broad tailing of the absorption of t Bu 3 P-IC 4 F 9 and (MeO) 3 P-IC 4 F 9 into the visible-light region. Larger coordinate displacements of the ground and excited singlet potential energy wells in n Bu 3 P-IC 4 F 9 , in particular with regard to the P-I-C bending angle, reduce the Franck-Condon factors and thus the absorption probability compared to t Bu 3 P-IC 4 F 9 . Spectroscopic and computational evaluation of conformationally flexible and locked phosphites suggests that the reactivity of (MeO) 3 P may be the result of oxygen lone-pair participation and concomitant broadening of absorption. The proposed mechanism for the phosphine-catalyzed homolytic C-I cleavage of perfluorobutane iodide involves S ← S absorption of the adduct followed by intersystem crossing to the photochemically active T 1 state.
Topics: Algorithms; Iodides; Light; Models, Theoretical; Molecular Conformation; Phosphines; Photochemical Processes; Quantum Theory; Spectrum Analysis
PubMed: 32244568
DOI: 10.3390/molecules25071606