Bidentate boron Lewis acids based on 1,8-diethynylanthracene were synthesised in two steps by initial stannylation of the terminal alkynes and subsequent tin-boron exchange with different chloroboranes. The reactions were very selective, and the target compounds were obtained in high purity and good to excellent yields. Complexation experiments of 1,8-bis[(diphenylboranyl)ethynyl]anthracene with nitrogen bases (pyridine, pyrimidine, TMEDA) afforded three stable adducts, which were structurally characterised by X-ray diffraction. Competition experiments demonstrated the selective exchange of guests, and quantum-chemical calculations provided information on their energetics. NMR experiments at low temperature gave insight into the dynamic behaviour of the TMEDA adduct.
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http://dx.doi.org/10.1002/anie.201812696 | DOI Listing |
Chemistry
January 2025
The University of Western Ontario, Department of Chemistry, 1151 Richmond St. N., N6A 5B7, London, CANADA.
The exploration of phosphorus-nitrogen heterocycles derived from chelating N-donor ligands is an area of research that has lagged behind the development of similar heterocycles based on other main group elements, most notably boron. The fact that phosphorus and nitrogen are both group 15 elements and that their compounds are most commonly viewed as Lewis bases likely contributes to this observation. However, through judicious ligand design and creative use of phosphorus sources that render phosphorus as Lewis acidic and/or electron poor, a variety of heterocyclic architectures are possible.
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August 2024
College of Life Science, China Jiliang University, Hangzhou, Zhejiang, China.
Boron difluoride (BF) complexes with asymmetrical N,N'-bidentate ligands have received increasing attention due to their fascinating properties and broad applications. They are generally constructed in two steps: ligand formation, followed by boron complexation. This review focuses on categorizing these BF complexes based on the key synthetic strategies that have been applied in the ligand formation steps.
View Article and Find Full Text PDFAcc Chem Res
June 2024
Department of Applied Chemistry, Waseda University, 513 Wasedatsurumakicho, Shinjuku, Tokyo 162-0041, Japan.
ConspectusAromatic esters are cost-effective, versatile, and commonly used scaffolds that are readily synthesized or encountered as synthetic intermediates. While most conventional reactions involving these esters are nucleophilic acyl substitutions or 1,2-nucleophilic additions─where a nucleophile attacks the carbonyl group, decarbonylative transformations offer an alternative pathway by using the carbonyl group as a leaving group. This transition-metal-catalyzed process typically begins with oxidative addition of the C(acyl)-O bond to the metal.
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May 2024
Chair of Inorganic and Structural Chemistry, Center for Molecular Materials CM2, Faculty of Chemistry, University of Bielefeld, Universitätsstraße 25, 33615 Bielefeld, Germany.
Four bidentate boron Lewis acids based on the 1,8-diethynylanthracene backbone have been synthesized by a tin-boron exchange reaction with various chloroboranes, yielding the products in good to excellent yields. Complexation experiments of the host compounds with pyridine, pyrimidine and TMEDA demonstrated striking differences in terms of formation and solubility of the supramolecular adducts. The host-guest complexes were investigated by multinuclear NMR spectroscopy and structurally characterized by X-ray diffraction experiments, illustrating the adaptation of the host system upon adduct formation with different neutral guest molecules.
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May 2024
Universität Bielefeld, Fakultät für Chemie, Lehrstuhl für Anorganische Chemie und Strukturchemie (ACS), Centre for Molecular Materials (CM2), Universitätsstr. 25, D-33615 Bielefeld, Germany.
Hexadentate poly-Lewis acids (PLA) based on the bowl-shaped tribenzotriquinacene (TBTQ) have been synthesised. The introduction of three -propyl groups into the benzhydrylic positions of the TBTQ backbone has significantly increased the solubility of the subsequently derived compounds. Semi-flexible PLAs containing boron and aluminium were obtained by hydrometallation of the corresponding 2,3,6,7,10,11-hexaalkynyl-TBTQ.
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