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Direct Observation of Polaritonic Chemistry by Nuclear Magnetic Resonance Spectroscopy. Angew Chem Int Ed Engl 2024; 63:e202401368. [PMID: 38584127 DOI: 10.1002/anie.202401368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 04/01/2024] [Accepted: 04/05/2024] [Indexed: 04/09/2024]
Abstract
Polaritonic chemistry is emerging as a powerful approach to modifying the properties and reactivity of molecules and materials. However, probing how the electronics and dynamics of molecular systems change under strong coupling has been challenging due to the narrow range of spectroscopic techniques that can be applied in situ. Here we develop microfluidic optical cavities for vibrational strong coupling (VSC) that are compatible with nuclear magnetic resonance (NMR) spectroscopy using standard liquid NMR tubes. VSC is shown to influence the equilibrium between two conformations of a molecular balance sensitive to London dispersion forces, revealing an apparent change in the equilibrium constant under VSC. In all compounds studied, VSC does not induce detectable changes in chemical shifts, J-couplings, or spin-lattice relaxation times. This unexpected finding indicates that VSC does not substantially affect molecular electron density distributions, and in turn has profound implications for the possible mechanisms at play in polaritonic chemistry under VSC and suggests that the emergence of collective behavior is critical.
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Rapid Access to Densely Functionalized Cyclopentenyl Sulfoximines through a Sc-Catalyzed Aza-Piancatelli Reaction. Org Lett 2024. [PMID: 38190622 DOI: 10.1021/acs.orglett.3c04095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
Sulfoximines make up a class of compounds of growing interest for crop science and medicinal chemistry, but methods for directly incorporating them into complex molecular scaffolds are lacking. Here we report a scandium-catalyzed variant of the aza-Piancatelli cyclization that can directly incorporate sulfoximines as nucleophiles rather than the classical aniline substrates. Starting from 2-furylcarbinols and sulfoximines, the reaction provides direct access to 4-sulfoximinocyclopentenones, a new scaffold bearing cyclopentenone and sulfoximine motifs, both of interest for bioactive compounds.
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3
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A single phosphorylation mechanism in early metabolism - the case of phosphoenolpyruvate. Chem Sci 2023; 14:14100-14108. [PMID: 38098731 PMCID: PMC10717536 DOI: 10.1039/d3sc04116f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 11/22/2023] [Indexed: 12/17/2023] Open
Abstract
Phosphorylation is thought to be one of the fundamental reactions for the emergence of metabolism. Nearly all enzymatic phosphorylation reactions in the anabolic core of microbial metabolism act on carboxylates to give acyl phosphates, with a notable exception - the phosphorylation of pyruvate to phosphoenolpyruvate (PEP), which involves an enolate. We wondered whether an ancestral mechanism for the phosphorylation of pyruvate to PEP could also have involved carboxylate phosphorylation rather than the modern enzymatic form. The phosphorylation of pyruvate with P4O10 as a model phosphorylating agent was found to indeed occur via carboxylate phosphorylation, as verified by mechanistic studies using model substrates, time course experiments, liquid and solid-state NMR spectroscopy, and DFT calculations. The in situ generated acyl phosphate subsequently undergoes an intramolecular phosphoryl transfer to yield PEP. A single phosphorylation mechanism acting on carboxylates appears sufficient to initiate metabolic networks that include PEP, strengthening the case that metabolism emerged from self-organized chemistry.
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Catalytic Synthesis of β-(Hetero)arylethylamines: Modern Strategies and Advances. Angew Chem Int Ed Engl 2023; 62:e202309289. [PMID: 37599269 DOI: 10.1002/anie.202309289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 08/18/2023] [Accepted: 08/19/2023] [Indexed: 08/22/2023]
Abstract
β-(Hetero)arylethylamines appear in a myriad of pharmaceuticals due to their broad spectrum of biological properties, making them prime candidates for drug discovery. Conventional methods for their preparation often require engineered substrates that limit the flexibility of the synthetic routes and the diversity of compounds that can be accessed. Consequently, methods that provide rapid and versatile access to those scaffolds remain limited. To overcome these challenges, synthetic chemists have designed innovative and modular strategies to access the β-(hetero)arylethylamine motif, paving the way for their more extensive use in future pharmaceuticals. This review outlines recent progresses in the synthesis of (hetero)arylethylamines and emphasizes how these innovations have enabled new levels of molecular complexity, selectivity, and practicality.
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Abstract
Under enzyme catalysis, adenosine triphosphate (ATP) transfers a phosphoryl group to canonical ribonucleotide diphosphates (NDPs) to form ribonucleotide triphosphates (NTPs), the direct biosynthetic precursors to RNA. However, it remains unclear whether the phosphorylation of NDPs could have occurred in water before enzymes existed and why an adenosine derivative, rather than another canonical NTP, typically performs this function. Here, we show that adenosine diphosphate (ADP) in the presence of Fe3+ or Al3+ promotes phosphoryl transfer from acetyl phosphate to all canonical NDPs to produce their corresponding NTP in water at room temperature and in the absence of enzymes. No other NDPs were found to promote phosphorylation, giving insight into why adenosine derivatives specifically became used for this purpose in biology. The metal-ADP complexes also promote phosphoryl transfer to ribonucleoside monophosphates (NMPs) to form a mixture of the corresponding NDPs and NTPs, albeit less efficiently. This work represents a rare example in which a single nucleotide carries out a function critical to biology without enzymes. ADP-metal complexes may have played an important role in nucleotide phosphorylation in prebiotic chemistry.
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Abstract
Vibrational strong coupling (VSC) occurs when molecular vibrations hybridize with the modes of an optical cavity, an interaction mediated by vacuum fluctuations. VSC has been shown to influence the rates and selectivity of chemical reactions. However, a clear understanding of the mechanism at play remains elusive. Here, we show that VSC affects the polarity of solvents, which is a parameter well-known to influence reactivity. The strong solvatochromic response of Reichardt's dye (RD) was used to quantify the polarity of a series of alcohol solvents at visible wavelengths. We observed that, by simultaneously coupling the OH and CH vibrational bands of the alcohols, the absorption maximum of Reichardt's dye redshifted by up to ∼15.1 nm, corresponding to an energy change of 5.1 kJ·mol-1. With aliphatic alcohols, the magnitude of the absorption change of RD was observed to be related to the length of the alkyl chain, the molecular surface area, and the polarizability, indicating that dispersion forces are impacted by strong coupling. Therefore, we propose that dispersion interactions, which themselves originate from vacuum fluctuations, are impacted under strong coupling and are therefore critical to understanding how VSC influences chemistry.
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Metal-Pyridoxal Cooperativity in Nonenzymatic Transamination. J Am Chem Soc 2023. [PMID: 37278531 DOI: 10.1021/jacs.3c03542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Coenzymes are involved in ≥30% of enzymatic reactions and likely predate enzymes, going back to prebiotic chemistry. However, they are considered poor organocatalysts, and thus their pre-enzymatic function remains unclear. Since metal ions are known to catalyze metabolic reactions in the absence of enzymes, here we explore the influence of metal ions on coenzyme catalysis under conditions relevant to the origin of life (20-75 °C, pH 5-7.5). Specifically, Fe or Al, the two most abundant metals in the Earth's crust, were found to exhibit substantial cooperative effects in transamination reactions catalyzed by pyridoxal (PL), a coenzyme scaffold used by roughly 4% of all enzymes. At 75 °C and 7.5 mol % loading of PL/metal ion, Fe3+-PL was found to be 90-fold faster at catalyzing transamination than PL alone and 174-fold faster than Fe3+ alone, whereas Al3+-PL was 85-fold faster than PL alone and 38-fold faster than Al3+ alone. Under milder conditions, reactions catalyzed by Al3+-PL were >1000 times faster than those catalyzed by PL alone. Pyridoxal phosphate (PLP) exhibited similar behavior to PL. Experimental and theoretical mechanistic studies indicate that the rate-determining step in the PL-metal-catalyzed transamination is different from metal-free and biological PL-based catalysis. Metal coordination to PL lowers the pKa of the PL-metal complex by several units and slows the hydrolysis of imine intermediates by up to 259-fold. Coenzymes, specifically pyridoxal derivatives, could have exhibited useful catalytic function even before enzymes.
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Synthesis of functionalised isochromans: epoxides as aldehyde surrogates in hexafluoroisopropanol. Chem Sci 2023; 14:2983-2989. [PMID: 36937595 PMCID: PMC10016621 DOI: 10.1039/d2sc06692k] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 02/13/2023] [Indexed: 02/17/2023] Open
Abstract
The oxa-Pictet-Spengler reaction is arguably the most straightforward and modular way to construct the privileged isochroman motif, but its scope is largely limited to benzaldehyde derivatives and to electron-rich β-phenylethanols that lack substitution along the aliphatic chain. Here we describe a variant of this reaction starting from an epoxide, rather than an aldehyde, that greatly expands the scope and rate of the reaction (<1 h, 20 °C). Besides facilitating the initial Meinwald rearrangement, the use of hexafluoroisopropanol (HFIP) as a solvent expands the electrophile scope to include partners equivalent to ketones, aliphatic aldehydes, and phenylacetyl aldehydes, and the nucleophile scope to include modestly electronically deactivated and highly substituted β-phenylethanols. The products could be easily further derivatised in the same pot by subsequent ring-opening, reductions, and intra- and intermolecular Friedel-Crafts reactions, also in HFIP. Finally, owing to the high pharmacological relevance of the isochroman motif, the synthesis of drug analogues was demonstrated.
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Synthesis of Unprotected β-Arylethylamines by Iron(II)-Catalyzed 1,2-Aminoarylation of Alkenes in Hexafluoroisopropanol. Angew Chem Int Ed Engl 2023; 62:e202215257. [PMID: 36541580 DOI: 10.1002/anie.202215257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 12/19/2022] [Accepted: 12/21/2022] [Indexed: 12/24/2022]
Abstract
β-Arylethylamines are prevalent structural motifs in molecules exhibiting biological activity. Here we report a sequential one-pot protocol for the 1,2-aminoarylation of alkenes with hydroxylammonium triflate salts and (hetero)arenes. Unlike existing methods, this reaction provides a direct entry to unprotected β-arylethylamines with remarkable functional group tolerance, allowing key drug-oriented functional groups to be installed in a two-step process. The use of hexafluoroisopropanol as a solvent in combination with an iron(II) catalyst proved essential to reaching high-value nitrogen-containing molecules.
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The effects of a soccer season on anthropometric characteristics, physical fitness, and soccer skills in North African elite female youth soccer players. Sci Sports 2023. [DOI: 10.1016/j.scispo.2022.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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Quantification of the hydride donor abilities of NADH, NADPH, and BH 3CN - in water. Org Biomol Chem 2022; 21:85-88. [PMID: 36472236 PMCID: PMC9768570 DOI: 10.1039/d2ob02041f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The nucleophilic reactivities of the hydride donors NADH, NADPH, and BH3CN- in water were quantified using kinetic measurements with benzhydrylium ions as reference electrophiles. All three hydride donors were found to possess almost identical nucleophilic reactivities, providing a potential explanation for why they are involved in similar transformations in biochemistry and organic synthesis, respectively.
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Synthesis of Unprotected β‐Arylethylamines by Iron(II)‐Catalyzed 1,2‐Aminoarylation of Alkenes in Hexafluoroisopropanol. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202215257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Hydrogen Drives Part of the Reverse Krebs Cycle under Metal or Meteorite Catalysis. Angew Chem Int Ed Engl 2022; 61:e202212932. [PMID: 36251920 PMCID: PMC10100321 DOI: 10.1002/anie.202212932] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Indexed: 11/24/2022]
Abstract
Hydrogen (H2 ) is a geological source of reducing electrons that is thought to have powered the metabolism of the last universal common ancestor to all extant life, and that is still metabolized by various modern organisms. It has been suggested that H2 drove a geochemical analogue of some or all of the reverse Krebs cycle at the emergence of the metabolic network, catalyzed by metals, but this has yet to be demonstrated experimentally. Herein, we show that three consecutive steps of the reverse Krebs cycle, converting oxaloacetate into succinate, can be driven without enzymes and in one-pot by H2 as the reducing agent under mild conditions compatible with biological chemistry. Low catalytic amounts of nickel (10-20 mol %) or platinum group metals (0.1-1 mol %) or even small amounts of ground meteorites were found to promote the reductive chemistry at temperatures between 5 and 60 °C and over a wide pH range, including pH 7. These results lend additional support to the hypothesis that geologically produced hydrogen and metal catalysts could have initiated early metabolic networks.
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Quantifying Reductive Amination in Nonenzymatic Amino Acid Synthesis. Angew Chem Int Ed Engl 2022; 61:e202212237. [PMID: 36121198 PMCID: PMC9828492 DOI: 10.1002/anie.202212237] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Indexed: 01/12/2023]
Abstract
Amino acid biosynthesis initiates with the reductive amination of α-ketoglutarate with ammonia to produce glutamate. However, the other α-keto acids derived from the glyoxylate and Krebs cycles are converted into amino acids by transamination, rather than by reductive amination. Why is only one amino acid synthesized by reductive amination and not the others? To explore this question, we quantified the inherent reactivities of keto acids in nonenzymatic reduction and reductive amination by using BH3 CN- as a model nucleophile. Biological α-keto acids were found to show pronounced nonenzymatic reactivity differences for the formation of amino acids (α-ketoglutarate<oxaloacetate≈pyruvate≪glyoxylate). Accordingly, the flow of ammonia passes through the least reactive α-keto acid of the Krebs cycle. One possible explanation for this choice is the position of the corresponding amino acid, glutamate, at the top of the thermodynamic landscape for subsequent transamination reactions.
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Hydrogen Drives Part of the Reverse Krebs Cycle under Metal or Meteorite Catalysis. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202212932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Quantifying Reductive Amination in Nonenzymatic Amino Acid Synthesis. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202212237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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17
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Leveraging the Hydroarylation of α-(Trifluoromethyl)styrenes to Access Trifluoromethylated All-Carbon Quaternary Centers. ACS Catal 2022. [DOI: 10.1021/acscatal.2c03330] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Bringing inanimate matter to life Transformer: The Deep Chemistry of Life and Death Nick Lane Norton, 2022. 400 pp. Science 2022; 377:39. [PMID: 35771908 DOI: 10.1126/science.abp8953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A biochemist probes the origins and vital nature of the Krebs cycle.
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Effect of Plyometric Jump Training on Skeletal Muscle Hypertrophy in Healthy Individuals: A Systematic Review With Multilevel Meta-Analysis. Front Physiol 2022; 13:888464. [PMID: 35832484 PMCID: PMC9271893 DOI: 10.3389/fphys.2022.888464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 05/18/2022] [Indexed: 11/28/2022] Open
Abstract
Objective: To examine the effect of plyometric jump training on skeletal muscle hypertrophy in healthy individuals. Methods: A systematic literature search was conducted in the databases PubMed, SPORTDiscus, Web of Science, and Cochrane Library up to September 2021. Results: Fifteen studies met the inclusion criteria. The main overall finding (44 effect sizes across 15 clusters median = 2, range = 1–15 effects per cluster) indicated that plyometric jump training had small to moderate effects [standardised mean difference (SMD) = 0.47 (95% CIs = 0.23–0.71); p < 0.001] on skeletal muscle hypertrophy. Subgroup analyses for training experience revealed trivial to large effects in non-athletes [SMD = 0.55 (95% CIs = 0.18–0.93); p = 0.007] and trivial to moderate effects in athletes [SMD = 0.33 (95% CIs = 0.16–0.51); p = 0.001]. Regarding muscle groups, results showed moderate effects for the knee extensors [SMD = 0.72 (95% CIs = 0.66–0.78), p < 0.001] and equivocal effects for the plantar flexors [SMD = 0.65 (95% CIs = −0.25–1.55); p = 0.143]. As to the assessment methods of skeletal muscle hypertrophy, findings indicated trivial to small effects for prediction equations [SMD = 0.29 (95% CIs = 0.16–0.42); p < 0.001] and moderate-to-large effects for ultrasound imaging [SMD = 0.74 (95% CIs = 0.59–0.89); p < 0.001]. Meta-regression analysis indicated that the weekly session frequency moderates the effect of plyometric jump training on skeletal muscle hypertrophy, with a higher weekly session frequency inducing larger hypertrophic gains [β = 0.3233 (95% CIs = 0.2041–0.4425); p < 0.001]. We found no clear evidence that age, sex, total training period, single session duration, or the number of jumps per week moderate the effect of plyometric jump training on skeletal muscle hypertrophy [β = −0.0133 to 0.0433 (95% CIs = −0.0387 to 0.1215); p = 0.101–0.751]. Conclusion: Plyometric jump training can induce skeletal muscle hypertrophy, regardless of age and sex. There is evidence for relatively larger effects in non-athletes compared with athletes. Further, the weekly session frequency seems to moderate the effect of plyometric jump training on skeletal muscle hypertrophy, whereby more frequent weekly plyometric jump training sessions elicit larger hypertrophic adaptations.
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Abstract
Metabolic theories for the origin of life posit that inorganic catalysts enabled self‐organized chemical precursors to the pathways of metabolism, including those that make genetic molecules. Recently, experiments showing nonenzymatic versions of a number of core metabolic pathways have started to support this idea. However, experimental demonstrations of nonenzymatic reaction sequences along the de novo ribonucleotide biosynthesis pathways are limited. Here we show that all three reactions of pyrimidine nucleobase biosynthesis that convert aspartate to orotate proceed at 60 °C without photochemistry under aqueous conditions in the presence of metals such as Cu2+ and Mn4+. Combining reactions into one‐pot variants is also possible. Life may not have invented pyrimidine nucleobase biosynthesis from scratch, but simply refined existing nonenzymatic reaction channels. This work is a first step towards uniting metabolic theories of life's origin with those centered around genetic molecules.
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Multiple Discrimination and Its Consequences for the Mental Health of Ethnic Minorities. Eur Psychiatry 2022. [PMCID: PMC9565626 DOI: 10.1192/j.eurpsy.2022.65] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Discrimination is a violation of human rights. The Universal Declaration of Human Rights proclaims in Art. 1 the equality of all human beings without distinction as to race, colour, sex, sexual orientation, religion, age or health. International law assigns three main characteristics to discrimination: disadvantageous treatment, based on unlawful grounds, and lack of reasonable and objective justification. Thus, it must be based on an unlawful characteristic: Ethnicity, religion, national or social origin, language, physical appearance, descent, gender, sexual orientation, age or disability. A growing body of literature has recognized health disparities and has investigated the relationship between discrimination and poor health outcomes. Ethnic minority groups across the world face social and psychological challenges linked to their minority status, often involving discrimination. Furthermore, cumulative exposure to racial discrimination has incremental negative long-term effects on the mental health of ethnic minority people.Studies that examine exposure to discrimination only at one point in time may underestimate the contribution of racism to poor health. Lower patient-centered care was associated with higher perceptions of discrimination, despite experiences of continuous discrimination or discrimination experienced as different types. Further, dissatisfaction with care was associated with discrimination, particularly when experienced in various forms. These findings reinforce a need for patient-provider communication that is inclusive and eliminates perceptions of discrimination and bias, increases patient-centeredness, and improves overall clinical care. Additionally, these results stress the need for more research investigating the relationship between discrimination and outcomes in patients, as perceived discrimination manifests as a significant barrier to effective disease management.
Disclosure
No significant relationships.
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A Nonenzymatic Analog of Pyrimidine Nucleobase Biosynthesis. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202117211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Hydroarylation of Enamides Enabled by HFIP via a Hexafluoroisopropyl Ether as Iminium Reservoir. Chem Sci 2022; 13:8436-8443. [PMID: 35919727 PMCID: PMC9297520 DOI: 10.1039/d2sc02012b] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 06/25/2022] [Indexed: 11/21/2022] Open
Abstract
Here we describe that HFIP greatly expands the scope with respect to both reaction partners of the Brønsted acid-catalyzed hydroarylation of enamides. The reaction is fast and practical and can...
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Unlocking the Friedel-Crafts arylation of primary aliphatic alcohols and epoxides driven by hexafluoroisopropanol. Chem 2021. [DOI: 10.1016/j.chempr.2021.10.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Desulfonative Suzuki-Miyaura Coupling of Sulfonyl Fluorides. Angew Chem Int Ed Engl 2021; 60:25307-25312. [PMID: 34570414 DOI: 10.1002/anie.202111977] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 09/23/2021] [Indexed: 12/16/2022]
Abstract
Sulfonyl fluorides have emerged as powerful "click" electrophiles to access sulfonylated derivatives. Yet, they are relatively inert towards C-C bond forming transformations, notably under transition-metal catalysis. Here, we describe conditions under which aryl sulfonyl fluorides act as electrophiles for the Pd-catalyzed Suzuki-Miyaura cross-coupling. This desulfonative cross-coupling occurs selectively in the absence of base and, unusually, even in the presence of strong acids. Divergent one-step syntheses of two analogues of bioactive compounds showcase the expanded reactivity of sulfonyl fluorides to encompass both S-Nu and C-C bond formation. Mechanistic experiments and DFT calculations suggest oxidative addition occurs at the C-S bond followed by desulfonation to form a Pd-F intermediate that facilitates transmetalation.
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108 COMBATTING CONFUSION: SIMULATION-BASED MEDICAL EDUCATION FOR DEALING WITH DELIRIUM. Age Ageing 2021. [DOI: 10.1093/ageing/afab219.108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023] Open
Abstract
Abstract
Background
Delirium is a complex, costly, and common clinical syndrome. Simulation-based medical education has been shown to be effective in enhancing the confidence, knowledge and skills of healthcare professionals in the management of delirium. We piloted an inter-professional education simulation on delirium in an acute hospital setting. The session’s design was informed by participating in ‘Sim Stars’, a regional simulation development competition.
Methods
We iteratively developed a low-fidelity simulation scenario on the recognition, prevention and management of delirium. The resulting simulation was piloted during an hour-long multidisciplinary departmental teaching session in a lecture hall setting. A candidate was asked to review an acutely confused patient (played by a ‘confederate’) on call. The candidate was expected to screen for delirium using the 4AT tool; assess for possible causes of delirium; and implement an appropriate management plan. After the session, qualitative feedback from the participants and audience was sought.
Results
This pilot simulation included one candidate (medical Senior House Officer); two confederates (Consultant Geriatrician, Advanced Nurse Practitioner); two facilitators (Consultant Geriatrician, Advanced Nurse Practitioner); and an audience of 17 members. Feedback indicated that learners and trainers found this a helpful and enjoyable pedagogical method. Areas for improvement were highlighted, including providing advance notice for learners of the topic to be simulated; a more structured introduction defining the learning outcomes and declaring a ‘blame free’ environment; improved script for the patient confederate; and that having a team of learners (rather than specialists) to play ‘confederates’ may help improve team-building and reduce learner anxiety.
Conclusion
This pilot simulation received positive appraisals from the team, and plans are underway to incorporate simulation more regularly into departmental teaching. Suggestions to improve future simulations were welcomed. Given its low-fidelity, this scenario can easily be used at any site for simulation-based training.
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Abstract
Several classes of biological reactions that are mediated by an enzyme and a co-factor can occur, to a slower extent, not only without the enzyme but even without the co-factor, under catalysis by metal ions. This observation has led to the proposal that metabolic pathways progressively evolved from using inorganic catalysts to using organocatalysts of increasing complexity. Transamination, the biological process by which ammonia is transferred between amino acids and α-keto acids, has a mechanism that has been well studied under enzyme/co-factor catalysis and under co-factor catalysis, but the metal ion-catalyzed variant was generally studied mostly at high temperatures (70-100 °C), and the details of its mechanism remained unclear. Here, we investigate which metal ions catalyze transamination under conditions relevant to biology (pH 7, 20-50 °C) and study the mechanism in detail. Cu2+, Ni2+, Co2+, and V5+ were identified as the most active metal ions under these constraints. Kinetic, stereochemical, and computational studies illuminate the mechanism of the reaction. Cu2+ and Co2+ are found to predominantly speed up the reaction by stabilizing a key imine intermediate. V5+ is found to accelerate the reaction by increasing the acidity of the bound imine. Ni2+ is found to do both to a limited extent. These results show that direct metal ion-catalyzed amino group transfer is highly favored even in the absence of co-factors or protein catalysts under biologically compatible reaction conditions.
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A landscape classification map of Ireland and its potential use in national land use monitoring. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2021; 289:112498. [PMID: 33878703 DOI: 10.1016/j.jenvman.2021.112498] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 03/04/2021] [Accepted: 03/26/2021] [Indexed: 06/12/2023]
Abstract
This study presents a novel landscape classification map of the Republic of Ireland and is the first to identify broad landscape classes by incorporating physiographic and land cover data. The landscape classification responds to commitments to identify and classify the Irish landscape as a signatory to the European Landscape Convention. The methodology applied a series of clustering iterations to determine an objective multivariate classification of physiographic landscape units and land cover datasets. The classification results determined nine statistically significant landscape classes and the development of a landscape classification map at a national scale. A statistical breakdown of land cover area and diversity of each class was interpreted, and a comparison was extended using independent descriptive variables including farmland use intensity, elevation, and dominant soil type. Each class depicts unique spatial and composition characteristics, from coastal, lowland and elevated, to distinct and dominating land cover types, further explained by the descriptive variables. The significance of individual classes and success of the classification is discussed with particular reference to the wider applicability of the map. The transferability of the methodology to other existing physiographic maps and environmental datasets to generate new landscape classifications is also considered. This novel work facilitates the development of a strategic framework to efficiently monitor, compare and analyse ecological and other land use data that is spatially representative of the distribution and extent of land cover in the Irish countryside.
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Participation of Glutamatergic Ionotropic Receptors in Excitotoxicity: The Neuroprotective Role of Prolactin. Neuroscience 2021; 461:180-193. [PMID: 33647379 DOI: 10.1016/j.neuroscience.2021.02.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 02/15/2021] [Accepted: 02/21/2021] [Indexed: 02/08/2023]
Abstract
Glutamate (Glu) is known as the main excitatory neurotransmitter in the central nervous system. It can trigger a series of processes ranging from synaptic plasticity to neurophysiological regulation. To carry out its functions, Glu acts via interaction with its cognate receptors, which are ligand-dependent. Glutamatergic receptors include ionotropic and metabotropic categories. The first allows the passage of ions through the postsynaptic membrane, while the metabotropic subtype activates signaling cascades through second messengers. It is well known that an excess of extracellular Glu concentration induces overstimulation of ionotropic glutamatergic receptors (iGluRs), causing the excitotoxicity phenomenon that leads to neuronal damage and cell death. Excitotoxicity plays a crucial role in different brain pathologies such as brain strokes, epilepsy and neurodegenerative disorders. However, until now, there are no effective neuroprotective compounds to prevent or rescue neurons from excitotoxicity. Thus, the continuous elucidation of the molecular mechanisms underlying excitotoxicity in order to prevent damage or neuronal death is necessary. Therefore, the aim of this review was to summarize the current knowledge regarding iGluRs, while describing their structures and molecular mechanisms of action, including their role in excitotoxicity, as well as the current strategies to reduce excitotoxic damage. Particularly, strategies mediated by prolactin, a somatotropin family-related hormone that displays a significant neuroprotective effect against both Glu and kainic acid-induced excitotoxicity in the hippocampus, are described. Finally, the role of prolactin as a possible molecule in the treatment of excitotoxicity in neurological diseases is discussed.
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Modifying Woodward-Hoffmann Stereoselectivity Under Vibrational Strong Coupling. Angew Chem Int Ed Engl 2021; 60:5712-5717. [PMID: 33305864 PMCID: PMC7986062 DOI: 10.1002/anie.202013465] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 11/18/2020] [Indexed: 11/23/2022]
Abstract
Vibrational strong coupling (VSC) has recently been shown to change the rate and chemoselectivity of ground‐state chemical reactions via the formation of light–matter hybrid polaritonic states. However, the observation that vibrational‐mode symmetry has a large influence on charge‐transfer reactions under VSC suggests that symmetry considerations could be used to control other types of chemical selectivity through VSC. Here, we show that VSC influences the stereoselectivity of the thermal electrocyclic ring opening of a cyclobutene derivative, a reaction which follows the Woodward–Hoffmann rules. The direction of the change in stereoselectivity depends on the vibrational mode that is coupled, as do changes in rate and reaction thermodynamics. These results on pericyclic reactions confirm that symmetry plays a key role in chemistry under VSC.
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Modifying Woodward–Hoffmann Stereoselectivity Under Vibrational Strong Coupling. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202013465] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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SINUS VENOSUS ATRIAL SEPTAL DEFECT WITH PARTIAL ANOMALOUS PULMONARY VENOUS DRAINAGE: A CASE REPORT OF A RARE CAUSE OF PULMONARY HYPERTENSION. Chest 2020. [DOI: 10.1016/j.chest.2020.08.1801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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MUCOEPIDERMOID CARCINOMA PRESENTING AS RECURRENT PNEUMONIA AND PERSISTENT COUGH IN A YOUNG ADULT MALE. Chest 2020. [DOI: 10.1016/j.chest.2020.08.1332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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A Supramolecular Model for the Co-Catalytic Role of Nitro Compounds in Brønsted Acid Catalyzed Reactions. Chemistry 2020; 26:10976-10980. [PMID: 32365243 DOI: 10.1002/chem.202000368] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Indexed: 11/09/2022]
Abstract
Nitro compounds are known to change reaction rates and kinetic concentration dependence of Brønsted-acid-catalyzed reactions. Yet, no mechanistic model exists to account for these observations. In this work, an atomistic model for the catalytically active form for an alcohol dehydroazidation reaction is presented, which is generated by DFT calculations and consists of an H-bonded aggregate of two molecules of Brønsted acid and two molecules of nitro compound. The computed O-H stretching frequencies for the aggregate indicate they are stronger acids than the individual acid molecules and serve as predictors for experimental reaction rates. By applying the model to a chemically diverse set of potential promoters, it was predicted and verified experimentally that sulfate esters induce a similar co-catalytic effect. The important implication is that Brønsted-acid catalysis must be viewed from a supramolecular perspective that accounts for not only the pKa of the acid and the bulk properties of a solvent, but also the weak interactions between all molecules in solution.
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Abstract
Prebiotic chemistry aims to explain how the biochemistry of life as we know it came to be. Most efforts in this area have focused on provisioning compounds of importance to life by multistep synthetic routes that do not resemble biochemistry. However, gaining insight into why core metabolism uses the molecules, reactions, pathways, and overall organization that it does requires us to consider molecules not only as synthetic end goals. Equally important are the dynamic processes that build them up and break them down. This perspective has led many researchers to the hypothesis that the first stage of the origin of life began with the onset of a primitive nonenzymatic version of metabolism, initially catalyzed by naturally occurring minerals and metal ions. This view of life's origins has come to be known as "metabolism first". Continuity with modern metabolism would require a primitive version of metabolism to build and break down ketoacids, sugars, amino acids, and ribonucleotides in much the same way as the pathways that do it today. This review discusses metabolic pathways of relevance to the origin of life in a manner accessible to chemists, and summarizes experiments suggesting several pathways might have their roots in prebiotic chemistry. Finally, key remaining milestones for the protometabolic hypothesis are highlighted.
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Brønsted Acid and H‐Bond Activation in Boronic Acid Catalysis. Chemistry 2020; 26:9883-9888. [DOI: 10.1002/chem.202001902] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Indexed: 01/15/2023]
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Ultrasound-guided transmuscular quadratus lumborum block catheter technique: a reply. Anaesthesia 2020; 75:414-415. [PMID: 32022913 DOI: 10.1111/anae.14990] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Exploiting hexafluoroisopropanol (HFIP) in Lewis and Brønsted acid-catalyzed reactions. Chem Commun (Camb) 2020; 56:11548-11564. [PMID: 32930690 DOI: 10.1039/d0cc05194b] [Citation(s) in RCA: 132] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Hexafluoroisopropanol (HFIP) is a solvent with unique properties that has recently gained attention for promoting a wide range of challenging chemical reactions. It was initially believed that HFIP was almost exclusively involved in the stabilization of cationic intermediates, owing to its high polarity and low nucleophilicity. However, in many cases, the mechanism of action of HFIP appears to be more complex. Recent findings reveal that many Lewis and Brønsted acid-catalyzed transformations conducted in HFIP additionally involve cooperation between the catalyst and HFIP hydrogen-bond clusters, akin to Lewis- or Brønsted acid-assisted-Brønsted acid catalysis. This feature article showcases the remarkable versatility of HFIP in Lewis and Brønsted acid-catalyzed reactions, with an emphasis on examples yielding mechanistic insight.
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Catalytic Synthesis of Trifluoromethylated Allenes, Indenes, Chromenes, and Olefins from Propargylic Alcohols in HFIP. J Org Chem 2019; 84:15926-15947. [DOI: 10.1021/acs.joc.9b02398] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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MASSIVE HEMOPTYSIS IN THE SETTING OF ACUTE MITRAL REGURGITATION. Chest 2019. [DOI: 10.1016/j.chest.2019.08.2032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Suzuki–Miyaura Coupling of (Hetero)Aryl Sulfones: Complementary Reactivity Enables Iterative Polyaryl Synthesis. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201908336] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Suzuki–Miyaura Coupling of (Hetero)Aryl Sulfones: Complementary Reactivity Enables Iterative Polyaryl Synthesis. Angew Chem Int Ed Engl 2019; 58:14959-14963. [DOI: 10.1002/anie.201908336] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 08/18/2019] [Indexed: 12/28/2022]
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Appraising, processing, and providing access to email in contemporary literary archives. ARCHIVES AND MANUSCRIPTS 2019. [DOI: 10.1080/01576895.2019.1622138] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Synthesis of new Mn 19 analogues and their structural, electrochemical and catalytic properties. Dalton Trans 2019; 48:4830-4836. [PMID: 30778455 DOI: 10.1039/c8dt04807j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the synthesis and structural characterisation of new Mn19 and Mn18M analogues, [MnIII12MnII7(μ4-O)8(μ3-OCH3)2(μ3-Br)6(HLMe)12(MeOH)6]Br2 (2) and [MnIII12MnII6Sr(μ4-O8(μ3-Cl)8(HLMe)12(MeCN)6]Cl2 cluster (3), where H3LMe is 2,6-bis(hydroxymethyl)-p-cresol. The electrochemistry of 2 and 3 has been investigated and their activity as catalysts in the oxidation of benzyl alcohol has been evaluated. Selective oxidation of benzyl alcohol to benzaldehyde by O2 was achieved using 1 mol% of catalyst with conversions of 74% (2) and 60% (3) at 140 °C using TEMPO as a co-catalyst. No partial conversion of benzaldehyde to benzoic acid was observed. The results obtained revealed that different operative parameters - such as catalyst loading, temperature, time, solvent and the presence of molecular oxygen - played an important role in the selective oxidation of benzyl alcohol.
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Tilting a ground-state reactivity landscape by vibrational strong coupling. Science 2019; 363:615-619. [DOI: 10.1126/science.aau7742] [Citation(s) in RCA: 312] [Impact Index Per Article: 62.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 01/08/2019] [Indexed: 01/18/2023]
Abstract
Many chemical methods have been developed to favor a particular product in transformations of compounds that have two or more reactive sites. We explored a different approach to site selectivity using vibrational strong coupling (VSC) between a reactant and the vacuum field of a microfluidic optical cavity. Specifically, we studied the reactivity of a compound bearing two possible silyl bond cleavage sites—Si–C and Si–O, respectively—as a function of VSC of three distinct vibrational modes in the dark. The results show that VSC can indeed tilt the reactivity landscape to favor one product over the other. Thermodynamic parameters reveal the presence of a large activation barrier and substantial changes to the activation entropy, confirming the modified chemical landscape under strong coupling.
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