Conjugated 1,5-diynes bearing two aromatic units at the alkyne termini were converted in the presence of a gold catalyst. Under mild conditions, aryl-substituted dibenzopentalenes were generated. Calculations predict that aurated vinyl cations are key intermediates of the reaction. A bidirectional approach provided selective access to the angular annulated product in high yield, which was explained by calculations.
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http://dx.doi.org/10.1002/anie.201700057 | DOI Listing |
Org Lett
January 2025
Key Laboratory of Precision and Intelligent Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China.
A 1,1-hydroboration of alkynylgermanes with unique -Ge/B stereochemistry under transition-metal-free conditions is reported. Mechanistic studies suggest that a pathway involving α-boration followed by a stepwise 1,2-Ge/H shift on the intermediate structurally lies between an alkyne-Ge π complex and a typical vinyl cation. The resulting Ge/B bimetallic modules, along with a /Ge/B trimetallic variant, can be conveniently transformed into trisubstituted olefins through iterative divergent cross-coupling.
View Article and Find Full Text PDFJ Phys Chem B
January 2025
School of Physics and Optoelectronic Engineering, Yangtze University, Jingzhou 434023, China.
Chromophores incorporated into rigid polymer matrices may exhibit novel photophysical properties distinct from those in liquid solutions. In this work, we explored the decay path of the second ππ* state (2ππ*) of riboflavin in poly(vinyl alcohol) (PVA) solutions and films with various acidities. Highly efficient internal conversion from 2ππ* to the lowest ππ* state (1ππ*) induced by slight in-plane motion is demonstrated in all PVA solutions and films, irrespective of environmental acidity and rigidification.
View Article and Find Full Text PDFMacromol Rapid Commun
January 2025
Institut für Chemie, Technische Universität Chemnitz, Straße der Nationen 62, 09111, Chemnitz, Germany.
Aromatic diimides such as naphthalene diimide (NDI) and pyromellitic diimide (MDI) are important building blocks for organic electrode materials. They feature a two-electron redox mechanism that allows for energy storage. Due to the smaller size of MDI compared to NDI its theoretical capacity is higher.
View Article and Find Full Text PDFOrg Chem Front
December 2024
Department of Chemistry, University of Pittsburgh Pittsburgh Pennsylvania 15260 USA
Org Lett
January 2025
Key Laboratory of Chemical Biology of Fujian Province and State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
Transition-metal-catalyzed [2 + 2 + 2] annulation of alkynes is an efficient pathway for the synthesis of aromatic compounds. However, most of the established methods require noble metal catalysts. Herein, we report a copper-catalyzed intermolecular [2 + 2 + 2] annulation of diynes with alkynes through vinyl cation intermediates, enabling the atom-economical preparation of biologically important carbazole skeletons.
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