Phosphinic Acid Research Articles

Rapid Generation of P(V)-F Bonds Through the Use of Sulfone Iminium Fluoride Reagents.

Phosphorus-fluorine bonds have become increasingly relevant in the pharmaceutical industry. To continue their exploration, more efficient synthetic methods are needed. Here, we report the application of sulfone iminium fluoride (SIF) reagents to the synthesis of P(V)-F bonds. The SIF reagents promote the deoxyfluorination of phosphinic acids in just 60 s with excellent yields and scope. The same P(V)-F products can also be synthesized from secondary phosphine oxides using an SIF reagent.

A leaching, solvent extraction, stripping, precipitation and calcination process for the recovery of MoO3 and NiO from spent hydrofining catalysts

Effective recovery of elements from spent catalysts can not only avoid environmental hazards, but also alleviate the pressure of resource scarcity. This study proposes a hydrometallurgical process for the selective recovery of MoO3 and NiO from the spent hydrofining catalysts. First, valuable metals were leached with 0.5 mol/L H2SO4 and 4 wt% H2O2 at 25 °C for 20 min, resulting in the dissolution efficiencies of Mo, Ni and Al were 95.6%, 96.5% and 13.8%, respectively. Then, bis-(2-ethylhexy)phosphinic acid (P227) was chosen as the Mo extractant due to its higher separation factors of βMo/Al and βMo/Fe compared to di-2-ethylhexylphosphoric acid (P204) and 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (P507). Extraction efficiency of 99.9% Mo was achieved at pH of 0.5 with 0.3 mol/L P227, whereas only 0.061 g/L Fe and <1 mg/L of other impurity elements were co-extracted. The complete stripping of Mo was realized with 0.4 mol/L (NH4)2CO3. Subsequently, a synergistic extraction system bis(2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex 301) and trioctylphosphine oxide (TOPO) was employed to extract Ni, where the extraction efficiency was more than 99.9%. Around 99.9% of Ni was stripped with 9 mol/L HCl. With the addition of TOPO, not only the extraction ability of Ni was improved, but also realized the complete stripping of Ni. The two oxides MoO3 and NiO were prepared from the stripping solution. In addition, the extraction mechanism of Mo and Ni was studied. The total recovery efficiencies of Mo and Ni were 94.1% and 93.1%, with the purity of 99.9% and 99.0%, indicating that this innovative process can be utilized to recover MoO3 and NiO from the spent hydrofining catalysts.

Microstructured silicon substrates impregnated with bis(2,4,4-trimethylpentyl) phosphinic acid for selective scandium recovery

The recovery of trace amounts of scandium from process tailings represents a challenging yet critical task for the growing demand for sustainable and renewable technologies. As an important step toward addressing the environmental and technical concerns related to current scandium separation approaches, we developed novel extractant-impregnated surfaces (EIS) that held a thin layer of extractant within a micropillar texturized substrate. Compared with traditional solvent extraction, the EIS requires significantly less volume of extractant and no agitation. About 95 % of scandium is separated from the complex feedstock prepared from industrial waste bauxite residue, and the selectivity of scandium is more than 200 times higher than that of aluminum. Adsorption isotherm and kinetic studies are performed, and the experimental data are in good agreement with the Langmuir isotherm model and indicate pseudo-second-order kinetics. Cryo time-of-flight secondary ion mass spectrometry depth profiling is conducted on post-extraction EIS to unveil the scandium ions transport behaviour. Moreover, it is confirmed the EIS scheme and its underlying principles can be applied to sandblasted polytetrafluoroethylene substrates, which proves the potential of using EIS design at larger scales.

Re-Examination of the Polymer Encapsulation of Quantum Dots for Biological Applications

The application of semiconductor core–shell quantum dots in biology requires the dispersion of these nanoparticles in water. A widely used phase transfer strategy is their encapsulation with amphiphilic polymers, a method that is believed to preserve the original ligand shell of quantum dots. In this contribution, we test this belief for the first time using a common encapsulation protocol based on poly(styrene-co-maleic anhydride) and ethanolamine and demonstrate that the original quantum dot ligand shell is in fact altered during the polymer encapsulation. In particular, our results show that primary amines, which are typically added to increase the hydrophilicity of the encapsulating polymer, displace the original ligands as a necessary step in the phase transfer process. We demonstrate that the surface of quantum dots synthesized using phosphinic acid as a ligand is readily modified by ethanolamine and hence shows high phase transfer efficiency, whereas quantum dots synthesized using oleic acid ligands did not show reactivity toward the primary amine and failed to transfer in the same conditions. Instead, a thiol, mercaptoethanol, was employed to displace the original oleic acid ligands and promote efficient poly(styrene-co-maleic anhydride) encapsulation. This work also provides practical guidelines for how the quantum dot community can better design and implement phase transfer protocols for a given composition, in order to maximize the efficiency and durability of the resulting water-dispersible nanoparticles for biological applications.

One-Step Synthesis of Benzophosphole Derivatives from Arylalkynes by Phosphenium-Dication-Mediated Sequential C-P/C-C Bond Forming Reaction.

A metal-free, phosphenium-dication-mediated sequential C-P and C-C bond forming reaction has been developed. This protocol can provide concise access to the (di)benzophosphole derivatives in one synthetic operation from the readily available and simple arylalkynes and phosphinic acids. Application to the multiple cyclization reaction and the fully intermolecular three-component-coupling-type reaction are also described.

New derivatives of phosphorus-containing compounds with amino acid and triazolethione ­fragments are potential drugs that improve memory and cognitive functions

Background. Cognitive disorders are often the main symptom of neurological and mental diseases. Given the variety of mechanisms for the development of these changes, it is necessary to search for and develop new drugs.&#x0D; Aim. An experimental study of the behavioral effects of new derivatives of phosphorus-containing compounds with amino acid and triazolethione fragments as potential agents that improve memory and cognitive functions.&#x0D; Material and methods. A computer prediction of the activity of 43 compounds (the Prediction Activity Spectral of Substances and Pharma expert programs) and the selection of 5 active compounds were carried out. The compounds were studied on 140 outbred male mice (14 groups, n=10) and 100 male Wistar rats (10 groups, n=10) in the T-maze and Morris water maze behavioral tests when administered intraperitoneally in doses 1/100 and 1/50 LD50 for 14 days. A comparative analysis with memantine (10 mg/kg), piracetam (100 mg/kg) and the structural analogue of the 2-chloroethoxy-para-N-dimethylaminophenylphosphorylacetohydrazide compounds (10 mg/kg) was carried out. Statistical processing was performed using the GraphPad prism 8.0.1 program with the calculation of Student's t-test.&#x0D; Results. The mnemotropic activity of N-substituted ammonium salts of arylphosphinic acids and phosphorylated derivatives of thiosemicarbazides was shown, the most effective representatives of which, 2-ethoxy-2-oxoethanammonium salt (2-ethoxy-2-oxotyl)(4-tolyl) of phosphinic acid (AH15) and 2-[(diphenyl phosphoryl)acetyl]-N-phenylhydrazine-1-carbothioamide (T8), reduced the time of searching for a feeder in the T-maze by 2.0 and 4.3 times, respectively (p 0.05). A similar effect was observed in the Morris Water Maze, where the use of substances T8 and 2-ethoxy-2-oxoethanammonium salt (2-ethoxy-2-oxotil)(4-chlorophenyl) of phosphinic acid (B3) on the 4th day of administration led to an increase in the time spent by rats in the platform area by 1.8 and 1.6 times (p 0.05), respectively, and on the 14th day by 1.5 times (p 0.05). Memantine and piracetam were only effective after 14 days of administration.&#x0D; Conclusion. Compounds of the series of N-substituted ammonium salts of arylphosphinic acids and phosphorylated derivatives of thiosemicarbazides improve memory and learning processes in experimental rodents with a single and 14-day application, showing significant advantages over memantine and piracetam.

Microbial biotransformation mechanisms of PFPiAs in soil unveiled by metagenomic analysis

As alternatives of long-chain PFASs (Poly- and perfluoroalkyl substances), perfluoroalkyl phosphinic acids (PFPiAs) are increasingly observed in the environment, but their environmental behaviors have not been well understood. Here, the microbial biotransformation of C6/C6 and C8/C8 PFPiA in two soils (Soil N and Y) was investigated. After 252 d and 330 d of incubation with PFPiAs in Soil N and Y respectively, the levels of PFPiAs decreased distinctly, accompanied by the increasing perfluorohexaphosphonic acid (PFHxPA) or perfluorooctanophosphonic acid (PFOPA) formation, magnifying PFPiAs were susceptible to C-P cleavage, which was also confirmed by the density functional theory calculations. The half-lives of the PFPiAs were longer than one year, while generally shorter in Soil N than in Soil Y and that of C6/C6 was shorter than C8/C8 PFPiA (392 d and 746 d in Soil N, and 603 and 1155 d in Soil Y, respectively). Metagenomic sequencing analysis revealed that Proteobacteria as the primary host of the potential functional genes related to CP bond cleavage might be the crucial phyla contributing to the biotransformation of PFPiAs. Meanwhile, the more intensive interactions between the microbes in Soil N consistently contribute to its greater capacity for transforming PFPiAs.

Design, Synthesis and Actual Applications of the Polymers Containing Acidic P-OH Fragments: Part 2-Sidechain Phosphorus-Containing Polyacids.

Macromolecules containing acidic fragments in side-groups—polyacids—occupy a special place among synthetic polymers. Properties and applications of polyacids are directly related to the chemical structure of macromolecules: the nature of the acidic groups, polymer backbone, and spacers between the main chain and acidic groups. The chemical nature of the phosphorus results in the diversity of acidic >P(O)OH fragments in sidechain phosphorus-containing polyacids (PCPAs) that can be derivatives of phosphoric or phosphinic acids. Sidechain PCPAs have many similarities with other polyacids. However, due to the relatively high acidity of −P(O)(OH)2 fragment, bone and mineral affinity, and biocompatibility, sidechain PCPAs have immense potential for diverse applications. Synthetic approaches to sidechain PCPAs also have their own specifics. All these issues are discussed in the present review.

PFAS Biotransformation Pathways: A Species Comparison Study

Limited availability of fish metabolic pathways for PFAS may lead to risk assessments with inherent uncertainties based only upon the parent chemical or the assumption that the biodegradation or mammalian metabolism map data will serve as an adequate surrogate. A rapid and transparent process, utilizing a recently created database of systematically collected information for fish, mammals, poultry, plant, earthworm, sediment, sludge, bacteria, and fungus using data evaluation tools in the previously described metabolism pathway software system MetaPath, is presented. The fish metabolism maps for 10 PFAS, heptadecafluorooctyl(tridecafluorohexyl)phosphinic acid (C6/C8 PFPiA), bis(perfluorooctyl)phosphinic acid (C8/C8 PFPiA), 2-[(6-chloro-1,1,2,2,3,3,4,4,5,5,6,6-dodecafluorohexyl)oxy]-1,1,2,2-tetrafluoroethanesulfonic acid (6:2 Cl-PFESA), N-Ethylperfluorooctane-1-sulfonamide (Sulfuramid; N-EtFOSA), N-Ethyl Perfluorooctane Sulfonamido Ethanol phosphate diester (SAmPAP), Perfluorooctanesulfonamide (FOSA), 8:2 Fluorotelomer phosphate diester (8:2 diPAP), 8:2 fluorotelomer alcohol (8:2 FTOH), 10:2 fluorotelomer alcohol (10:2 FTOH), and 6:2 fluorotelomer sulfonamide alkylbetaine (6:2 FTAB), were compared across multiple species and systems. The approach demonstrates how comparisons of metabolic maps across species are aided by considering the sample matrix in which metabolites were quantified for each species, differences in analytical methods used to identify metabolites in each study, and the relative amounts of metabolites quantified. Overall, the pathways appear to be well conserved across species and systems. For PFAS lacking a fish metabolism study, a composite map consisting of all available maps would serve as the best basis for metabolite prediction. This emphasizes the importance and utility of collating metabolism into a searchable database such as that created in this effort.

Binding Affinity of Monoalkyl Phosphinic Acid Ligands toward Nanocrystal Surfaces

We recently introduced monoalkyl phosphinic acids as a ligand class for nanocrystal (NC) synthesis. Their metal salts have interesting reactivity differences compared to metal carboxylates and phosphonates and provide a cleaner work-up compared to phosphonates. However, little is known about the surface chemistry of NCs with monoalkyl phosphinate ligands. Here, we probe the relative binding affinity of monoalkyl phosphinate ligands with respect to other X-type ligands. We perform competitive ligand exchange reactions with carboxylate and phosphonate ligands at the surface of hafnia, cadmium selenide, and zinc sulfide NCs. We monitor the ligand shell composition by solution 1H and 31P NMR spectroscopy. Using a monoalkyl phosphinic acid with an ether functionality, we gain an additional NMR signature, apart from the typical alkene resonance in oleic acid and oleylphosphonic acid. We find that carboxylate ligands are easily exchanged upon exposure to monoalkyl phosphinic acids, whereas an equilibrium is reached between monoalkyl phosphinates and phosphonates, slightly in the favor of phosphonate (K = 2). Phosphinic acids have thus an intermediate binding affinity between carboxylic acids and phosphonic acids for all the NCs studied. These results enable the sophisticated use of monoalkyl phosphinic acids for NC synthesis and for post-synthetic surface engineering.

Selective Extraction of Hafnium over Zirconium with Dialkylphosphinic Acids from H2SO4 Media

Designing highly efficient dialkylphosphinic acid extractant for zirconium/hafnium separation relies on systematic structure-property studies. In this paper, dialkylphosphinic acids with different substituents at β-C, γ-C and δ-C for zirconium and hafnium extraction and separation from H2SO4 media were investigated. The results show that substituents at β-C, γ-C and δ-C reduce the extraction ability of dialkylphosphinic acids for both zirconium and hafnium. The substituent effect at β-C is greater than that at γ-C and δ-C. The larger steric hindrance of the substituents (ethyl &gt; methyl &gt; H), the weaker extraction ability of the dialkylphosphinic acids. The zirconium and hafnium separation behavior is related to the extraction ability of dialkylphosphinic acids. Dialkylphosphinic acids with stronger extraction ability show better zirconium/hafnium separation performance at higher acidity of 2.0 mol L-1 H2SO4, while those with weaker extraction ability show better zirconium and hafnium separation performance at lower acidity of 0.25 mol L-1 H2SO4. The highest hafnium/zirconium separation factor (βHf/Zr) in the current study occurs with (2-ethylhexyl) (2,4,4-trimethylpentyl)phosphinic acid (USTB-1), which reaches 19.2.

ОПРЕДЕЛЕНИЕ ПЛОТНОСТИ И ДИЭЛЕКТРИЧЕСКОЙ ПРОНИЦАЕМОСТИ РАСТВОРОВ РЕДКОЗЕМЕЛЬНЫХ ЭЛЕМЕНТОВ СРЕДНЕТЯЖЕЛОЙ ГРУППЫ В ВОДНЫХ РАСТВОРАХ И В ЭКСТРАКТАХ КИСЛЫХ ФОСФОРОРГАНИЧЕСКИХ ЭКСТРАГЕНТОВ

Co-extraction of rare-earth elements from chloride solutions containing total rare-earth elements by a mixture of extractants mono-2-ethylhexyl ester of 2-ethylhexylphosphonic acid (P507) + di(2,2,4-trimethylpentyl)phosphinic acid (Cyanex 272) + 10 about. % TBP in isopar-l with a mass concentration of P507 + Cyanex 272 - 15%. The density and permittivity of solutions of rare-earth elements of the medium-heavy group in aqueous solutions and in extracts of acidic organophosphorus extractants have been determined. Initial concentrations in REE GH solutions ranged from 0.15 to 1.7 mol/dm3. The features of complex formation in a mixture of praseodymium metal and P507 extractant were studied. The initial concentrations in praseodymium solutions ranged from 0.014 to 0.149 mol/dm3.

Low-carbon footprint diluents in solvent extraction for lithium-ion battery recycling.

This study investigated the influence of the diluent on the extraction properties of three extractants towards cobalt(ii), nickel(ii), manganese(ii), copper(ii), and lithium(i), i.e. Cyanex® 272 (bis-(2,4,4-trimethylpentyl)phosphinic acid), DEHPA (bis-(2-ethyl hexyl)phosphoric acid), and Acorga® M5640 (alkylsalicylaldehyde oxime). The diluents used in the formulation of the extraction solvents are (i) low-odour aliphatic kerosene produced from the petroleum industry (ELIXORE 180, ELIXORE 230, ELIXORE 205 and ISANE IP 175) and (ii) bio-sourced aliphatic diluents (DEV 2138, DEV 2139, DEV 1763, DEV 2160, DEV 2161 and DEV 2063). No influence of the diluent and no co-extraction of lithium(i), nickel(ii), cobalt(ii), manganese(ii) and aluminum were observed during copper(ii) extraction by Acorga M5640. The nature of the diluent influenced more significantly the extraction properties of manganese(ii) by DEHPA as well as cobalt(ii) and nickel(ii) by Cyanex® 272. Life cycle assessment of the diluents shows that the carbon footprints of the investigated diluents followed the following order: (ELIXORE 180, ELIXORE 230, ELIXORE 205) from petroleum industry > kerosene from petroleum industry > diluent produced from tall oil (DEV 2063) > diluents produced from recycled plastic (DEV 2160, DEV 2161) > diluents produced from used cooking oil (DEV 2138, DEV 2139). By taking into account the physicochemical properties of these diluents (viscosity, flashpoint, aromatic content), the extraction properties of Acorga® M5640, DEHPA, Cyanex® 272 in these diluents and the CO2 footprint of the diluents, this study showed DEV2063 and DEV2139 were the best diluents. A low-carbon footprint solvent extraction flowsheet using these diluents was proposed to extract selectively cobalt, nickel, manganese, lithium and copper from NMC black mass of spent lithium-ion batteries.

Oxidation Kinetics of some Lower Oxyacids of Phosphorus by Picolinium Chlorochromate: Determination of Reactive Reducing Species

Picolinium chlorochromate (PICC) in dimethylsuloxide (DMSO) oxidizes lower oxyacids of phosphorus, forming matching oxyacids with phosphorus in a higher oxidation state. The reaction shows a stoichiometry of 1:1. In relation to PICC, the response is first order. Regarding the reductants, a kinetics of the Michaelis-Menten type was noticed. Acrylonitrile does not undergo polymerization as a result of the reaction. Hydrogen ions function as catalysts for reactions. The form of the hydrogen-ion dependency is: kobs = a + b[H+]. Deuterated phosphinic and phenylphosphinic acids showed a significant primary kinetic isotope impact during oxidation. Nineteen different organic solvents were used to study the oxidation. The multiparametric equations of Taft and Swain were used to analyze the solvent effects. The influence of the solvent shows that the polarity of the solvent is crucial to the process. The penta-coordinated tautomer of the phosphorus oxyacid has been shown to be the reactive reductant, and it has been determined that the tricoordinated forms of phosphorus oxyacids do not take part in the oxidation process. It has been hypothesized that the rate-determining phase involves the transfer of a hydride ion.

Ag10Cu16 nanoclusters with triple-ligand protection: total structure and electronic structure analysis.

Illustrating the molecular structure of metal nanoclusters with the protection of multiple ligands is a prerequisite to understand structure-property relationships of nano or bulk materials with hybrid interfaces. Reported herein is the synthesis, total structure and electronic structure analysis of a new Ag/Cu alloy nanocluster with triple-ligand protection. The cluster with the formula of Ag10Cu16(C8H9S)16(PPh3)4(CF3CO2)8 has been attained in one-pot in a simple way. X-ray single crystal analysis displays its unique metal framework and more importantly rich interface structures. The ligands of phosphine, thioate and carboxylic acid are coordinated to the surface of the cluster in distinctive modes. The electronic structure of the cluster has been revealed by density functional theory, showing that it is a 2-electron superatom with jellium configurations of 1S2. In good accordance with the closure of the geometric and electronic structures, the cluster exhibits moderate stability, which makes it a candidate for further application in many fields.

Biologically active calixarene phosphonic acids

Phosphorylated derivatives of organic compounds are known to be capable of inhibiting the activities of enzymes and other proteins responsible for key metabolic pathways. In this connection, the calixarene phosphonic acids are of interest as macrocyclic agents interacting with targets that may be involved in pathological cellular processes. This review presents a literature survey on the synthesis and properties of calix[4]arene phosphonic acids as inhibitors of alkaline phosphatases, protein tyrosine phosphatases, Na,K-ATPase, nucleotide pyrophosphatase/phosphodiesterase 1, and some other enzymes and proteins. Brief information is also given about the inhibitory activity of calix[4]arene derivatives bearing alkyl phosphonate or phosphinic acid groups

Purification of Carrier-Free 47Sc of Biomedical Interest: Selective Separation Study from natCa(n,γ)

47Sc for theranostic medical applications was produced from the neutron activation of a natural calcium target. Liquid–liquid extraction for separation of the 47Sc radioisotope from 47Ca was carried out with the extractant Cyanex 272 ((2,4,4-trimethylpentyl) phosphinic acid). The effects of various extraction parameters on the extraction efficiency and separation of the two radionuclides were investigated, including the extraction time, pH, metal ion concentrations, extractant concentration, diluent type, and phase ratio. It was shown that the extraction yield of the 47Sc radioisotope with the proposed procedure is about 90%, with a fast separation time of 10 min, at pH 1.8 (0.01 M HCl), and with low E (1%) for 47Ca and high separation factors. The stripping % of the loaded 47Sc isotope was about 99.2% using 0.4 M oxalic acid solution with a purity of 99.9%.

Preparation and properties of phosphinic acid-functionalized polyacrylonitrile hollow fiber membrane for heavy metal adsorption.

In this study, phosphorylated polyacrylonitrile hollow fiber membrane was synthesized by reacting aminated polyacrylonitrile hollow fiber membrane with phosphinic acid in a Mannich reaction. The batch single-factor measurements revealed that the phosphorylated polyacrylonitrile (PPAN) membrane had an outstanding ability for Hg2+ adsorption. Thermodynamic investigations indicated that the adsorption process was homogenous, and the theoretical maximum adsorption capacity predicted by the Langmuir model was 371.75mg·g-1. The PPAN membrane was able to successfully chelate Hg2+ ions and attain saturation in 4h, demonstrating that the reaction was chemically controlled by the adsorption kinetics. Based on the FT-IR and XPS spectral characterization data, successful phosphinic acid group grafting was proven, and a plausible mechanism for Hg2+ adsorption by PPAN membranes was presented. Furthermore, the five adsorption-desorption cycle experiments revealed that PPAN hollow fiber membranes had outstanding reusability, indicating a possible use for removing heavy metal ions from wastewater.

Phosphinic Peptides as Tool Compounds for the Study of Pharmacologically Relevant Zn-Metalloproteases.

Phosphinic peptides constitute an important class of bioactive compounds that have found a wide range of applications in the field of biology and pharmacology of Zn-metalloproteases, the largest family of proteases in humans. They are designed to mimic the structure of natural substrates during their proteolysis, thus acting as mechanism-based, transition state analogue inhibitors. A combination of electrostatic interactions between the phosphinic acid group and the Zn cation as well as optimal noncovalent enzyme-ligand interactions can result in both high binding affinity for the desired target and selectivity against other proteases. Due to these unique properties, phosphinic peptides have been mainly employed as tool compounds for (a) the purposes of rational drug design by serving as ligands in X-ray crystal structures of target enzymes and allowing the identification of crucial interactions that govern optimal molecular recognition, and (b) the delineation of biological pathways where Zn-metalloproteases are key regulators. For the latter objective, inhibitors of the phosphinopeptidic type have been used either unmodified or after being transformed to probes of various types, thus expanding the arsenal of functional tools available to researchers. The aim of this review is to summarize all recent research achievements in which phosphinic peptides have played a central role as tool compounds in the understanding of the mechanism and biological functions of Zn-metalloproteases in both health and disease.

Reppe‐Carbonylation of Alkenes with Carboxylic Acids: A Catalytic and Mechanistic Study

AbstractIn this work, a green‐catalytic procedure is used to demonstrate the synthesis of long‐chain anhydrides. This is accomplished by the carbonylation of alkenes with carboxylic acids. Anhydrides are important intermediates, finding specific applications as acetylation agents. The process is catalyzed by a Pd phosphine catalyst system in the presence of an acid promotor. Through optimization experiments, the importance of the phosphine ligand and acid promotor is demonstrated, without which the catalyst shows no activity. Although the yield was limited because of catalyst deactivation (42 %), to the best of our knowledge, the synthesis of long‐chain anhydrides through this route have not been reported previously. It therefore represents a significant result. Isolation of the anhydrides were also successfully demonstrated, however, as a result of the sensitivity of the anhydrides to water, the isolated yields were much lower than the HPLC yield. Furthermore, a mechanistic study by means of HP‐NMR (High Pressure Nuclear Magnetic Resonance) spectroscopy provided significant insights into the mechanism of the reaction.