Publications by authors named "Peter G Jones"

374 Publications

Crystal structures of the gold NHC complex bis-(4-bromo-1,3-di-ethyl-imidazol-2-yl-idene)gold(I) iodide and its 1:1 adduct with -bis-(4-bromo-1,3-diethyl-imidazol-2-yl-idene)di-iodido-gold(III) iodide.

Acta Crystallogr E Crystallogr Commun 2021 Dec 9;77(Pt 12):1249-1252. Epub 2021 Nov 9.

Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany.

The first title compound, [Au(CHBrN)]I, crystallizes in the space group without imposed symmetry. The cations and anions are linked to form chains by Br⋯I⋯Br halogen-bond linkages. The second title compound, [Au(CHBrN)][AuI(CHBrN)]I, is an adduct of the first and its formally I-oxidized Au analogue. It also crystallizes in space group , whereby both gold atoms occupy inversion centres. The extended structure is a reticular layer involving Br⋯I⋯Br and I⋯I⋯Au linkages.
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http://dx.doi.org/10.1107/S2056989021011488DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8647741PMC
December 2021

Crystal structure of 2-{[5-amino-1-(phenyl-sulfon-yl)-1-pyrazol-3-yl]-oxy}-1-(4-methyl-phen-yl)ethan-1-one.

Acta Crystallogr E Crystallogr Commun 2021 Oct 30;77(Pt 10):1054-1057. Epub 2021 Sep 30.

Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany.

In the title compound, CHNOS, the pyrazole ring is planar, with the sulfur atom lying 0.558 (1) Å out of the ring plane. The NH group is involved in an intra-molecular hydrogen bond to a sulfonyl oxygen atom; its other hydrogen atom forms an asymmetric three-centre hydrogen bond to the two oxygen atoms of the -O-CH-C=O- grouping, the 2 screw axis, forming a ribbon structure parallel to the axis. Translationally adjacent, coplanar ribbons form a layer parallel to (10).
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http://dx.doi.org/10.1107/S2056989021010008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8491526PMC
October 2021

Alkyne Aminopalladation/Heck and Suzuki Cascades: An Approach to Tetrasubstituted Enamines.

Chemistry 2021 Oct 14;27(60):14846-14850. Epub 2021 Oct 14.

Technische Universität Braunschweig, Institute of Organic Chemistry, Hagenring 30, 38106, Braunschweig, Germany.

Alkyne aminopalladation reactions starting from tosylamides are reported. The emerging vinylic Pd species are converted either in an intramolecular Heck reaction with olefinic units or in an intermolecular Suzuki reaction by using boronic acids exhibiting broad functional group tolerance. Tetra(hetero)substituted tosylated enamines are obtained in a simple one-pot process.
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http://dx.doi.org/10.1002/chem.202103567DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8596888PMC
October 2021

Phosphine-Catalyzed Aryne Oligomerization: Direct Access to α,ω-Bisfunctionalized Oligo(-arylenes).

J Am Chem Soc 2021 Oct 29;143(40):16796-16803. Epub 2021 Sep 29.

Clausthal University of Technology, Institute of Organic Chemistry, Leibnizstrasse 6, 38678 Clausthal-Zellerfeld, Germany.

A phosphine-catalyzed oligomerization of arynes using selenocyanates was developed. The use of JohnPhos as a bulky phosphine is the key to accessing α,ω-bisfunctionalized oligo(-arylenes) with RSe as the substituent at one terminus and CN as the substituent at the other. The formation of RPSeR' cations, serving as sterically encumbered electrophiles, hinders the immediate reaction that affords the 1,2-bisfunctionalization product and instead opens a competitive pathway leading to oligomerization. Various optimized conditions for the predominant formation of dimers, but also for higher oligomers such as trimers and tetramers, were developed. Depending on the electronic properties of the electrophilic reaction partner, even compounds up to octamers were isolated. Optimization experiments revealed that a properly tuned phosphine as catalyst is of crucial importance. Mechanistic studies demonstrated that the cascade starts with the attack of cyanide; aryne insertion into -mers leading to (+1)-mers was ruled out.
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http://dx.doi.org/10.1021/jacs.1c08689DOI Listing
October 2021

Crystal structure of '-[2-(benzo[]thia-zol-2-yl)acet-yl]benzohydrazide, an achiral compound crystallizing in space group 1 with = 1.

Acta Crystallogr E Crystallogr Commun 2021 Sep 3;77(Pt 9):891-894. Epub 2021 Aug 3.

Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany.

In the mol-ecule of the title compound, CHNOS, one hydrazinic nitro-gen atom is essentially planar, but the other is slightly pyramidalized. The torsion angle about the hydrazinic bond is 66.44 (15)°. Both hydrazinic hydrogen atoms lie anti-periplanar to the oxygen of the adjacent carbonyl group. The mol-ecular packing is a layer structure determined by two classical hydrogen bonds, N-H⋯O=C and N-H⋯N. The space group is 1 with = 1, which is unusual for an achiral organic compound.
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http://dx.doi.org/10.1107/S2056989021007672DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8423019PMC
September 2021

Cycloadditions of Donor-Acceptor Cyclopropanes and -butanes using S=N-Containing Reagents: Access to Cyclic Sulfinamides, Sulfonamides, and Sulfinamidines.

Angew Chem Int Ed Engl 2021 12 29;60(49):25825-25831. Epub 2021 Oct 29.

Technische Universität Braunschweig, Institute of Organic Chemistry, Hagenring 30, 38106, Braunschweig, Germany.

We present (3+2)- and (4+2)-cycloadditions of donor-acceptor (D-A) cyclopropanes and cyclobutanes with N-sulfinylamines and a sulfur diimide, along with a one-pot, two-step strategy for the formal insertion of HNSO into D-A cyclopropanes. These are rare examples of cycloadditions with D-A cyclopropanes and cyclobutanes whereby the 2π component consists of two different heteroatoms, thus leading to five- and six-membered rings containing adjacent heteroatoms.
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http://dx.doi.org/10.1002/anie.202106596DOI Listing
December 2021

Gold(I) and Gold(III) N-Heterocyclic Carbene Complexes as Antibacterial Agents and Inhibitors of Bacterial Thioredoxin Reductase.

ChemMedChem 2021 Nov 3;16(22):3402-3409. Epub 2021 Aug 3.

Institute of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Beethovenstrasse 55, 38106, Braunschweig, Germany.

A series of (NHC)Au(I)Cl monocarbene complexes and their gold(III) analogues (NHC)Au(III)Cl were prepared and investigated as antibacterial agents and inhibitors of bacterial TrxR. The complexes showed stronger antibacterial effects against the Gram-positive MRSA and E. faecium strains than against several Gram-negative bacteria. All complexes were efficient inhibitors of bacterial thioredoxin reductase, indicating that inhibition of this enzyme might be involved in their mechanism of action. The efficacy of gold(I) and gold(III) analogues was comparable in most of the assays. The cytotoxicity of the gold NHC compounds against cancer and human cells was overall weaker than the activity against the Gram-positive bacteria, suggesting that their optimization as antibacterials warrants further investigation.
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http://dx.doi.org/10.1002/cmdc.202100381DOI Listing
November 2021

Crystal structure of ethyl 2-(3-amino-5-oxo-2-tosyl-2,5-di-hydro-1-pyrazol-1-yl)acetate.

Acta Crystallogr E Crystallogr Commun 2021 Jun 14;77(Pt 6):615-617. Epub 2021 May 14.

Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany.

In the title compound, CHNOS, the five-membered ring is essentially planar. The substituents at the nitro-gen atoms subtend a C-N-N-S torsion angle of -95.52 (6)°. The amino group forms an intra-molecular hydrogen bond to a sulfonyl oxygen atom; two inter-molecular hydrogen bonds from the amino group, to the other S=O group and to the oxo substituent, form a layer structure parallel to the plane. The structure determination confirms that the title compound is - rather than -alkyl-ated.
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http://dx.doi.org/10.1107/S2056989021004795DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8183440PMC
June 2021

Crystal structure of potassium tri-ethyl-hydridoborate ('superhydride').

Acta Crystallogr E Crystallogr Commun 2021 Jun 7;77(Pt 6):592-595. Epub 2021 May 7.

Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany.

In the title compound, formally K·CHB, the contact sphere of potassium consists of eleven hydrogen atoms from three different anions, assuming an arbitrary cut-off of 3 Å. The shortest inter-action, 2.53 (2) Å, involves the hydridic hydrogen H01, which fulfils a bridging function in the formation of chains of KHBEt units parallel to the axis [K1-H01 2.71 (2) Å, K1-H01-K1 126.7 (9)°, operators ∓1/2, - + , - + 1].
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http://dx.doi.org/10.1107/S2056989021004734DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8183439PMC
June 2021

Crystal structures of ()-2-amino-4-methyl-sulfanyl-6-oxo-1-(1-phenyl-ethyl-idene-amino)-1,6-di-hydro-pyrimidine-5-carbo-nitrile and ()-2-amino-4-methyl-sulfanyl-6-oxo-1-[1-(pyridin-2-yl)ethyl-idene-amino]-1,6-di-hydro-pyrimidine-5-carbo-nitrile.

Acta Crystallogr E Crystallogr Commun 2021 May 23;77(Pt 5):547-550. Epub 2021 Apr 23.

Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany.

The title compounds , CHNOS, and , CHNOS, both show an configuration about the N=C bond and a planar NH group. The mol-ecules, which only differ in the presence of a phenyl (in ) or pyridyl (in ) substituent, are closely similar except for the different orientations of these groups. The amino hydrogen atoms form classical hydrogen bonds; in the acceptors are the oxygen atom and the cyano nitro-gen atom, leading to ribbons of mol-ecules parallel to the axis, whereas in the acceptors are the oxygen atom and the pyridyl nitro-gen, leading to a layer structure perpendicular to (01).
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http://dx.doi.org/10.1107/S2056989021004126DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8100259PMC
May 2021

Electrocatalytic Activation of Donor-Acceptor Cyclopropanes and Cyclobutanes: An Alternative C(sp )-C(sp ) Cleavage Mode.

Angew Chem Int Ed Engl 2021 Jul 16;60(29):15928-15934. Epub 2021 Jun 16.

Technische Universität Braunschweig, Institute of Organic Chemistry, Hagenring 30, 38106, Braunschweig, Germany.

We describe the first electrochemical activation of D-A cyclopropanes and D-A cyclobutanes leading after C(sp )-C(sp ) cleavage to the formation of highly reactive radical cations. This concept is utilized to formally insert molecular oxygen after direct or DDQ-assisted anodic oxidation of the strained carbocycles, delivering β- and γ-hydroxy ketones and 1,2-dioxanes electrocatalytically. Furthermore, insights into the mechanism of the oxidative process, obtained experimentally and by additional quantum-chemical calculations are presented. The synthetic potential of the reaction products is demonstrated by diverse derivatizations.
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http://dx.doi.org/10.1002/anie.202101477DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8362004PMC
July 2021

Azide-Functionalized Derivatives of the Virulence-Associated Sugar Pseudaminic Acid: Chiral Pool Synthesis and Labeling of Bacteria.

Chemistry 2021 Jul 2;27(41):10595-10600. Epub 2021 May 2.

Technische Universität Braunschweig, Institute of Organic Chemistry, Hagenring 30, 38106, Braunschweig, Germany.

Pseudaminic acid (Pse) is a significant prokaryotic monosaccharide found in important Gram-negative and Gram-positive bacteria. This unique sugar serves as a component of cell-surface-associated glycans or glycoproteins and is associated with their virulence. We report the synthesis of azidoacetamido-functionalized Pse derivatives as part of a search for Pse-derived metabolic labeling reagents. The synthesis was initiated with d-glucose (Glc), which served as a cost-effective chiral pool starting material. Key synthetic steps involve the conversion of C1 of Glc into the terminal methyl group of Pse, and inverting deoxyaminations at C3 and C5 of Glc followed by backbone elongation with a three-carbon unit using the Barbier reaction. Metabolic labeling experiments revealed that, of the four Pse derivatives, ester-protected C5 azidoacetamido-Pse successfully labeled cells of Pse-expressing Gram-positive and Gram-negative strains. No labeling was observed in cells of non-Pse-expressing strains. The ester-protected and C5 azidoacetamido-functionalized Pse is thus a useful reagent for the identification of bacteria expressing this unique virulence-associated nonulosonic acid.
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http://dx.doi.org/10.1002/chem.202100443DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8360151PMC
July 2021

Regio- and Diastereoselective Copper-Catalyzed Carbomagnesiation for the Synthesis of Penta- and Hexa-Substituted Cyclopropanes.

Angew Chem Int Ed Engl 2021 05 14;60(21):11804-11808. Epub 2021 Apr 14.

Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion City, Haifa, 3200009, Israel.

Despite the highly strained nature of cyclopropanes possessing three vicinal quaternary carbon stereocenters, the regio- and diastereoselective copper-catalyzed carbomagnesiation reaction of cyclopropenes provides an easy and efficient access to these novel persubstituted cyclopropyl cores with a complete regio- and diastereoselectivity.
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http://dx.doi.org/10.1002/anie.202102509DOI Listing
May 2021

Review article: Emergency department crowding measures associations with quality of care: A systematic review.

Emerg Med Australas 2021 08 16;33(4):592-600. Epub 2021 Mar 16.

Simpson Centre for Health Services Research, The University of New South Wales, Sydney, New South Wales, Australia.

ED crowding has been reported to reduce the quality of care. There are many proposed crowding metrics, but the metric most strongly associated with care quality remains unknown. The present study aims to determine the crowding metric with the strongest links with processes and outcomes of care linked to the Institute of Medicine quality domains. Systematic searches in healthcare databases were conducted using terms for 'crowding', 'metrics' and 'performance', supplemented by grey literature and citation searches. The level of evidence for each association was assessed using an explicit tool. The body of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation approach. Evidence was synthesised using harvest plots. Titles and abstracts of 2052 studies were screened, 452 selected for full-text review and 183 included. Inter-observer agreement was moderate κ = 0.54 (95% confidence interval 0.50-0.59). Two thirds were from urban tertiary hospitals in North America (65%), Australasia (13%), Europe (12%) and Asia (8%). One third provided Level 3 or higher evidence. Metrics were based on occupancy (38%), time (31%), workload (19%) or combinations (9%). Data were synthesised from 25 607 375 patients, 2368 staff, 9089 hospitals and 101 177 sampling times. Almost all crowding metrics were patient-centred and reflect timeliness and efficiency. ED length of stay, boarding time and total occupancy had the strongest association with safety and effectiveness of care. ED length of stay was also associated with equity. The certainty of evidence for associations between crowding measures varied across domains of quality, from very low to moderate certainty.
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http://dx.doi.org/10.1111/1742-6723.13743DOI Listing
August 2021

Referral for investigation: a redundant SNOMED-CT chief presenting complaint.

N Z Med J 2021 02 5;134(1529):39-44. Epub 2021 Feb 5.

Adult Emergency Department, Auckland City Hospital, Auckland District Health Board.

Aim: The Ministry of Health has mandated that all emergency department (ED) presentations are coded using the Systematised Nomenclature of Medicine - Clinical Terms (SNOMED-CT) from 2021. The current ED reference set contains the non-specific term 'Referral for investigation' in the list of available chief presenting complaints (CPCs). The aim of this study was to determine the rate of use of this term and how often a more specific (and therefore more clinically useful) term was used.

Method: This was a cross-sectional audit of routinely collected presenting complaint data, supplemented by a retrospective case note review.

Results: 'Referral for investigation' was used for 497/9,067 (5.5%, 95%CI 5-6%) presentations, with increased use for urgent cases. An alternative CPC was available in 467/497 (94.0%, 95%CI 92-96%) of cases from the existing reference set. Of 98 different CPCs, the common alternatives were: 'Chest pain' (6.4%), 'Shortness of breath' (4.2%) 'Abdominal pain' (3.6%), 'Altered mental status' (3.4%) and 'Postoperative complication' (3.2%). Six of 13 cardiac arrests and eight of 63 of multiple trauma cases were coded as 'Referral for investigation'. With the addition of two new terms to the New Zealand reference set ('Abnormal blood test' and 'Radiology request'), each of the remaining 30 presentations would have an alternative and more accurate CPC.

Conclusion: 'Referral for investigation' should be removed from the New Zealand emergency department reference set for chief presenting complaints to improve data quality.
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February 2021

GlycoBODIPYs: Sugars Serving as a Natural Stock for Water-soluble Fluorescent Probes of Complex Chiral Morphology.

Angew Chem Int Ed Engl 2021 04 17;60(16):8766-8771. Epub 2021 Mar 17.

TU Braunschweig, Institute of Organic Chemistry, Hagenring 30, 38106, Braunschweig, Germany.

A range of unprocessed, reducing sugar substrates (mono-, di-, and trisaccharides) is shown to take part in a straightforward four-step synthetic route to water-soluble, uncharged BODIPY derivatives with unimpaired chiral integrity and high fluorescence efficiency. A wide compatibility with several postfunctionalizations is demonstrated, thus suggesting a universal utility of the multifunctional glycoconjugates, which we call GlycoBODIPYs. Knoevenagel condensations are able to promote a red-shift in the spectra, thereby furnishing strongly fluorescent red and far-red glycoconjugates of high hydrophilicity. The synthetic outcome was studied by X-ray crystallography and by comprehensive photophysical investigations in several solvent systems. Furthermore, cell experiments illustrate efficient cell uptake and demonstrate differential cell targeting as a function of the integrated chiral information.
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http://dx.doi.org/10.1002/anie.202016764DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8048574PMC
April 2021

One-Pot Strategy for Symmetrical and Unsymmetrical BOIMPY Fluorophores.

J Org Chem 2021 Feb 14;86(3):3089-3095. Epub 2021 Jan 14.

Technische Universität Braunschweig, Institute of Organic Chemistry, Hagenring 30, 38106 Braunschweig, Germany.

We report the improved direct access to red-emitting BOIMPY fluorophores (λ ≈ 600 nm) via a simple one-pot approach. Our method starts from easily available benzimidazole-2-carboxylic acids and not only greatly improves the overall yields but also saves both costly reagents and time. In addition, the method facilitates the synthesis of novel unsymmetrical BOIMPY motifs. Therefore, these BOIMPY scaffolds derived from the BODIPY core become more accessible for applications as fluorophores at the appealing red edge of the visible spectrum.
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http://dx.doi.org/10.1021/acs.joc.0c02860DOI Listing
February 2021

Accuracy of SNOMED-CT Chief Presenting Complaint Codes: an audit of 1,000 cases.

N Z Med J 2020 12 4;133(1526):67-75. Epub 2020 Dec 4.

House Officer, Auckland City Hospital, Auckland.

Aim: The Systematised Nomenclature of Medicine - Clinical Terms (SNOMED-CT) coding system has been introduced to emergency departments in New Zealand, starting with the patient's chief presenting complaint (CPC). However, it is not known how accurate CPC coding at triage is, or whether coding accuracy varies by patient characteristics. The aim of this study was to determine the accuracy of CPC coding.

Method: We compared the real-time triage recorded CPC with the presenting complaints recorded in medical notes by the treating clinician. Agreement was determined by exact CPC matches and the kappa statistic.

Results: From 1,000 consecutive presentations 852 were eligible (89 CPCs). Real-time CPC agreed with clinical notes in 514/852 (60.3%) cases. When real-time free text comments were included, agreement was 732/852 (85.9%). There were no differences by age, sex or ethnicity. Agreement for the common CPCs: 'trauma' (21%); 'abdominal pain' (11%), 'chest pain' 87 (10%) and 'shortness of breath' (8%) was substantial, k=0.66 (95% CI: 0.61, 0.70). Use of non-specific CPC such as 'referral for investigation' (5%) and 'general weakness/fatigue/unwell' (2%) was uncommon but associated with poor agreement.

Conclusion: The accuracy of real-time coding for CPC using SNOMED-CT was reasonable, except for non-specific CPCs, which should be avoided where possible.
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December 2020

Emergency department crowding and mortality for patients presenting to emergency departments in New Zealand.

Emerg Med Australas 2021 08 10;33(4):655-664. Epub 2020 Dec 10.

Epidemiology and Biostatistics, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand.

Objective: The association between ED crowding and mortality has been established internationally, but not in New Zealand. The aim was to determine which measures of crowding were associated with mortality for new patients presenting to New Zealand EDs. The primary outcome was mortality for patients within 7 days of arrival in the ED.

Methods: This was a retrospective cohort study, using administrative data from 2006 to 2012. The crowding conditions at the time of presentation of each patient were recreated. Multivariable Cox proportional hazard modelling was used to determine the probability of death within 7 days of the presentation to ED. Each crowding measure was added independently to the optimum mortality model to determine how each crowding metric influenced the model.

Results: Twenty-five of 28 (89%) eligible acute hospitals in New Zealand were included, with 5 793 767 ED visits by 2 214 865 individuals. Seven-day mortality was higher for patients arriving at times when there was more than 10% hospital access block (hazard ratio [HR] 1.10, 95% confidence interval [CI] 1.05, 1.17) or non-compliance with the 4-h emergency access target (HR 1.07, 95% CI 1.01, 1.12). ED occupancy did not influence the model importantly, while the number of arrivals in the previous 6 h was associated with lower mortality (HR 0.90, 95% CI 0.84, 0.97).

Conclusion: Access block had the strongest association with 7-day mortality. That ED occupancy and the number of arrivals were not associated with increased mortality suggests that system issues related to long ED stays may be most important in the link between ED crowding and mortality.
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http://dx.doi.org/10.1111/1742-6723.13699DOI Listing
August 2021

Crystal structure of the unusual coordination polymer -poly[[gold(I)-μ-1,2-bis-(di-phenyl-phosphino-thio-yl)ethane-κ :'] di-bromido-aurate(I)].

Acta Crystallogr E Crystallogr Commun 2020 Nov 20;76(Pt 11):1768-1770. Epub 2020 Oct 20.

Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany.

In the title compound, {[Au(CHPS)][AuBr]} , the gold(I) centres of the cation are coordinated by the P=S groups of the di-sulfide ligands to form a chain polymer parallel to the axis. Both independent gold atoms lie on the same twofold axis, and the midpoint of the HC-CH bond lies on an inversion centre. The anions flank the polymeric chain; they are connected to it by short aurophilic inter-actions and C-H⋯Br contacts, and to each other by Br⋯Br contacts.
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http://dx.doi.org/10.1107/S2056989020013675DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7643243PMC
November 2020

An Approach to Paracyclophane-Based Tetrathiafulvalenes: Synthesis and Characterization of a [2.2]Paracyclophane 1,3-Dithia-2-Thione.

Molecules 2020 Nov 11;25(22). Epub 2020 Nov 11.

Institute of Organic Chemistry, Technical University of Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany.

The synthesis of paracyclophane-based tetrathiafulvalene precursors is described in the context of the importance of these compounds in the field of material chemistry. bis(1,3-dithia-2-thione) was synthesized via the corresponding 1,3-dithiol-2-ylium salt. The latter was obtained by a synthetic procedure that involves 4,15-bis(acetyl)[2.2]paracyclophane, a new compound of interest for many researchers.
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http://dx.doi.org/10.3390/molecules25225262DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7698277PMC
November 2020

(3 + 2)-Cycloaddition of Donor-Acceptor Cyclopropanes with Selenocyanate: Synthesis of Dihydroselenophenes and Selenophenes.

Org Lett 2020 Nov 27;22(21):8720-8724. Epub 2020 Oct 27.

Technische Universität Braunschweig, Institute of Organic Chemistry, Hagenring 30, 38106 Braunschweig, Germany.

We present a Lewis-acid-catalyzed (3 + 2)-cycloaddition of donor-acceptor cyclopropanes and selenocyanate (as its tetramethylammonium salt) for the synthesis of dihydroselenophenes. The transformation proceeded with moderate to excellent yields and showed a high functional group tolerance. Further oxidation using DDQ delivered selenophenes.
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http://dx.doi.org/10.1021/acs.orglett.0c03329DOI Listing
November 2020

Quantification of Noncovalent Interactions in Azide-Pnictogen, -Chalcogen, and -Halogen Contacts.

Chemistry 2021 Mar 8;27(14):4627-4639. Epub 2021 Feb 8.

Technische Universität Braunschweig, Institut für Organische Chemie, Hagenring 30, 38106, Braunschweig, Germany.

The noncovalent interactions between azides and oxygen-containing moieties are investigated through a computational study based on experimental findings. The targeted synthesis of organic compounds with close intramolecular azide-oxygen contacts yielded six new representatives, for which X-ray structures were determined. Two of those compounds were investigated with respect to their potential conformations in the gas phase and a possible significantly shorter azide-oxygen contact. Furthermore, a set of 44 high-quality, gas-phase computational model systems with intermolecular azide-pnictogen (N, P, As, Sb), -chalcogen (O, S, Se, Te), and -halogen (F, Cl, Br, I) contacts are compiled and investigated through semiempirical quantum mechanical methods, density functional approximations, and wave function theory. A local energy decomposition (LED) analysis is applied to study the nature of the noncovalent interaction. The special role of electrostatic and London dispersion interactions is discussed in detail. London dispersion is identified as a dominant factor of the azide-donor interaction with mean London dispersion energy-interaction energy ratios of 1.3. Electrostatic contributions enhance the azide-donor coordination motif. The association energies range from -1.00 to -5.5 kcal mol .
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http://dx.doi.org/10.1002/chem.202004525DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7986704PMC
March 2021

Extended Benzene-Fused Oligo-BODIPYs: In Three Steps to a Series of Large, Arc-Shaped, Near-Infrared Dyes.

Angew Chem Int Ed Engl 2021 Jan 9;60(2):747-752. Epub 2020 Nov 9.

Technische Universität Braunschweig, Institute of Organic Chemistry, Hagenring 30, 38106, Braunschweig, Germany.

We present a straightforward, three-step synthesis engaging an oligomerization and subsequent one-pot oxidation step to form fully conjugated, benzene-fused oligo-BODIPYs from simple BODIPY precursors. FeCl serves as an efficient, bifunctional oxidant for a (multiple) cyclization/desaturation process, applied to ethylene-bridged dimeric, trimeric and oligomeric species to transform linking ethano units into stiff benzene fusions between unsubstituted β-positions of each BODIPY unit. The structural integrity was verified by X-ray crystallography, and all target compounds were studied in detail by photophysical, electrochemical and computational means. The main S excited state gradually converges to a structure-specific excitation limit, displaying a strong shift of the absorption event from about 500 nm (BODIPY monomer) to 955 nm (octamer) with attenuation coefficients up to ca. 500 000 M  cm .
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http://dx.doi.org/10.1002/anie.202012335DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7839587PMC
January 2021

Novel HDAC/Tubulin Dual Inhibitor: Design, Synthesis and Docking Studies of α-Phthalimido-Chalcone Hybrids as Potential Anticancer Agents with Apoptosis-Inducing Activity.

Drug Des Devel Ther 2020 3;14:3111-3130. Epub 2020 Aug 3.

Institute of Inorganic and Analytical Chemistry, Braunschweig, Germany.

Introduction: In order to develop novel anticancer HDAC/tubulin dual inhibitors, a novel series of α-phthalimido-substituted chalcones-based hybrids was synthesized and characterized by IR, H NMR, C NMR, mass spectroscopy and X-ray analysis.

Methods: All the synthesized compounds were evaluated for their in vitro anticancer activity against MCF-7 and HepG2 human cancer cell lines using MTT assay. To explore the mechanism of action of the synthesized compounds, in vitro -tubulin polymerization and HDAC 1 and 2 inhibitory activity were measured for the most potent anticancer hybrids. Further, cell cycle analysis was also evaluated.

Results: The trimethoxy derivative showed the most potent anticancer activity, possessed the most potent -tubulin polymerase and HDAC 1 and 2 inhibitory activity and efficiently induced cell cycle arrest at both G2/M and preG1phases in the MCF-7 cell line.
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http://dx.doi.org/10.2147/DDDT.S256756DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7425103PMC
July 2021

-Selective, Enantiospecific Addition of Donor-Acceptor Cyclopropanes to Activated Alkenes: An Iodination/Michael-Cyclization Cascade.

Org Lett 2020 Aug 4;22(16):6404-6408. Epub 2020 Aug 4.

We present a versatile method for the enantiospecific, -diastereoselective intermolecular and intramolecular cycloaddition of donor-acceptor cyclopropanes to electron-poor alkenes with cyclic acceptor groups to afford highly substituted spirocyclopentanes in good to excellent yields. The reaction can be applied to biologically interesting scaffolds, including barbiturates and isoxazolones. Mechanistic investigations were undertaken to explain the unusual diastereoselectivity and enantiospecificity; these suggest an iodination/Michael-cyclization cascade.
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http://dx.doi.org/10.1021/acs.orglett.0c02210DOI Listing
August 2020

Enantiomerically Pure Constrained Geometry Complexes of the Rare-Earth Metals Featuring a Dianionic N-Donor Functionalised Pentadienyl Ligand: Synthesis and Characterisation.

Chemistry 2020 Dec 17;26(68):16098-16110. Epub 2020 Nov 17.

Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106, Braunschweig, Germany.

We report the preparation of enantiomerically pure constrained geometry complexes (cgc) of the rare-earth metals bearing a pentadienyl moiety (pdl) derived from the natural product (1R)-(-)-myrtenal. The potassium salt 1, [Kpdl*], was treated with ClSiMe NHtBu, and the resulting pentadiene 2 was deprotonated with the Schlosser-type base KOtPen/nBuLi (tPen=CMe (CH Me)) to yield the dipotassium salt [K (pdl*SiMe NtBu)] (3). However, 3 rearranges in THF solution to its isomer 3' by a 1,3-H shift, which elongates the bridge between the pdl and SiMe NtBu moieties by one CH unit. This is crucial for the successful formation of various monomeric C - or dimeric C -symmetric rare-earth cgc complexes with additional halide, tetraborohydride, amido and alkyl functionalities. All compounds have been extensively characterised by solid-state X-ray diffraction analysis, solution NMR spectroscopy and elemental analyses.
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http://dx.doi.org/10.1002/chem.202003170DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7756846PMC
December 2020

Pd-Catalyzed Cyanoselenylation of Internal Alkynes: Access to Tetrasubstituted Selenoenol Ethers.

Org Lett 2020 Jul 17;22(13):5025-5029. Epub 2020 Jun 17.

The intra- and intermolecular synthesis of selenium-substituted acyclic and heterocyclic acrylonitrile derivatives is presented. The 1,2-difunctionalization of several internal alkynes substituted not only by aliphatic and aromatic residues but also by heteroelements is realized by the Pd-catalyzed activation of aromatic and aliphatic selenocyanates. A high functional group tolerance allows straightforward access to a broad scope of tetrasubstituted olefins. X-ray studies of some products reveal noncovalent chalcogen-chalcogen interactions between oxygen and selenium.
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http://dx.doi.org/10.1021/acs.orglett.0c01582DOI Listing
July 2020

NH formation from N and H mediated by molecular tri-iron complexes.

Nat Chem 2020 08 29;12(8):740-746. Epub 2020 Jun 29.

Technische Universität Braunschweig, Institut für Anorganische und Analytische Chemie, Braunschweig, Germany.

Living systems carry out the reduction of N to ammonia (NH) through a series of protonation and electron transfer steps under ambient conditions using the enzyme nitrogenase. In the chemical industry, the Haber-Bosch process hydrogenates N but requires high temperatures and pressures. Both processes rely on iron-based catalysts, but molecular iron complexes that promote the formation of NH on addition of H to N have remained difficult to devise. Here, we isolate the tri(iron)bis(nitrido) complex [(Cp'Fe)(μ-N)] (in which Cp' = η-1,2,4-(MeC)CH), which is prepared by reduction of [Cp'Fe(μ-I)] under an N atmosphere and comprises three iron centres bridged by two μ-nitrido ligands. In solution, this complex reacts with H at ambient temperature (22 °C) and low pressure (1 or 4 bar) to form NH. In the solid state, it is converted into the tri(iron)bis(imido) species, [(Cp'Fe)(μ-NH)], by addition of H (10 bar) through an unusual solid-gas, single-crystal-to-single-crystal transformation. In solution, [(Cp'Fe)(μ-NH)] further reacts with H or H to form NH.
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http://dx.doi.org/10.1038/s41557-020-0483-7DOI Listing
August 2020

Ferrocenyl-substituted tetrahydrothiophenes via formal [3 + 2]-cycloaddition reactions of ferrocenyl thioketones with donor-acceptor cyclopropanes.

Beilstein J Org Chem 2020 10;16:1288-1295. Epub 2020 Jun 10.

Technische Universität Braunschweig, Institute of Organic Chemistry, Hagenring 30, 38106 Braunschweig, Germany.

Ferrocenyl thioketones reacted with donor-acceptor cyclopropanes in dichloromethane at room temperature in the presence of catalytic amounts of Sc(OTf) yielding tetrahydrothiophene derivatives, products of formal [3 + 2]-cycloaddition reactions, in moderate to high yields. In all studied cases, dimethyl 2-arylcyclopropane dicarboxylates reacted with the corresponding aryl ferrocenyl thioketones in a completely diastereoselective manner to form single products in which (C-2)-Ar and (C-5)-ferrocenyl groups were oriented in a -fashion. In contrast, the same cyclopropanes underwent reaction with alkyl ferrocenyl thioketones to form nearly equal amounts of both diastereoisomeric tetrahydrothiophenes. A low selectivity was also observed in the reaction of a 2-phthalimide-derived cyclopropane with ferrocenyl phenyl thioketone.
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http://dx.doi.org/10.3762/bjoc.16.109DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7296194PMC
June 2020
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