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Kvin Guillier Elsa Caytan Vincent Dorcet Florence Mongin lise Dumont Floris Chevallier 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(42):15082-15085
A halogen‐bond templated 1:1 macrocyclization in solution is reported. Tetra(iodoperfluorophenyl) ethers were used as halogen‐bonded exotemplates in a substoichiometric amount (5 mol %). Pyridine‐containing macrocyclic architectures were formed by ruthenium‐catalyzed tandem metathesis/transfer hydrogenation sequence using sodium borohydride and methanol as non‐dihydrogen hydrogen source. The halogen‐bonded stabilization energies were analyzed relying on density functional theory. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(26):7761-7765
The umpolung alkylation of silyl enol ethers with an iodonium(III) ylide proceeds under mild conditions to afford various 1,4‐dicarbonyl compounds in high yields in the presence of a halogen‐bonding catalyst. Unlike typical transition‐metal activation processes of such ylide precursors, which tend to proceed via carbenoid intermediates, experimental and computational studies indicate that halogen bonding (XB) between the XB donor catalyst and the iodonium ylide plays a crucial role in promoting the reaction. The identification of a compatible Bronsted base catalyst enabled the extension of this method to enols generated in situ to give the corresponding adducts in good yields. 相似文献
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Benjamin R. Mullaney Amber L. Thompson Paul D. Beer 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(43):11851-11851
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Xinxing Zhang Gaoxiang Liu Sandra Ciborowski Wei Wang Chu Gong Yifan Yao Kit Bowen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(33):11522-11525
Halogen bonding (XB) has emerged as an important bonding motif in supramolecules and biological systems. Although regarded as a strong noncovalent interaction, benchmark measurements of the halogen bond energy are scarce. Here, a combined anion photoelectron spectroscopy and density functional theory (DFT) study of XB in solvated Br? anions is reported. The XB strength between the positively‐charged σ‐hole on the Br atom of the bromotrichloromethane (CCl3Br) molecule and the Br? anion was found to be 0.63 eV (14.5 kcal mol?1). In the neutral complexes, Br(CCl3Br)1,2, the attraction between the free Br atom and the negatively charged equatorial belt on the Br atom of CCl3Br, which is a second type of halogen bonding, was estimated to have interaction strengths of 0.15 eV (3.5 kcal mol?1) and 0.12 eV (2.8 kcal mol?1). 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(33):10029-10032
Both hydrogen bonding (HB) and halogen bonding (XB) are essentially electrostatic interactions, but whereas hydrogen bonding has a well‐documented record of stabilizing unstable anions, little is known about halogen bonding's ability to do so. Herein, we present a combined anion photoelectron spectroscopic and density functional theory study of the halogen bond‐stabilization of the pyrazine (Pz) anion, an unstable anion in isolation due to its neutral counterpart having a negative electron affinity (EA). The halogen bond formed between the σ‐hole on bromobenzene (BrPh) and the lone pair(s) of Pz significantly lowers the energies of the Pz(BrPh)1− and Pz(BrPh)2− anions relative to the neutral molecule, resulting in the emergence of a positive EA for the neutral complexes. As seen through its charge distribution and electrostatic potential analyses, the negative charge on Pz− is diluted due to the XB. Thermodynamics reveals that the low temperature of the supersonic expansion plays a key role in forming these complexes. 相似文献
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Chuan‐Zhi Liu Satish Koppireddi Hui Wang Dan‐Wei Zhang Zhan‐Ting Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(1):232-236
Halogen bonding has been used to glue together hydrogen‐bonded short arylamide foldamers to achieve new supramolecular double and quadruple helices in the solid state. Three compounds, which bear a pyridine at one end and either a CF2I or fluorinated iodobenzene group at the other end, engage in head‐to‐tail N???I halogen bonds to form one‐component supramolecular P and M helices, which stack to afford supramolecular double‐stranded helices. One of the double helices can dimerize to form a G‐quadruplex‐like supramolecular quadruple helix. Another symmetric compound, which bears a pyridine at each end, binds to ICF2CF2I through N???I halogen bonds to form two‐component supramolecular P and M helices, with one turn consisting of four (2+2) molecules. Half of the pyridine‐bearing molecules in two P helices and two M helices stack alternatingly to form another supramolecular quadruple helix. Another half of the pyridine‐bearing molecules in such quadruple helices stack alternatingly with counterparts from neighboring quadruple helices, leading to unique quadruple helical arrays in two‐dimensional space. 相似文献
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Patrick Wonner Alexander Dreger Lukas Vogel Elric Engelage Stefan M. Huber 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(47):17079-17083
Chalkogenbrücken sind nicht‐kovalente Wechselwirkungen zwischen Lewis‐aziden Chalkogensubstituenten und Lewis‐Basen. Hierin präsentieren wir die erste Anwendung dikationischer, Tellur‐basierter Chalkogenbrückendonoren als Katalysatoren in einer Nitro‐Michael‐Reaktion zwischen trans‐β‐Nitrostyrol und Indolen. Dies ist außerdem die erste Aktivierung einer Nitro‐Gruppe durch Chalkogenbrücken (und Halogenbrücken). Die Katalysatoren zeigten eine mehr als 300‐fache Beschleunigung der Reaktionsgeschwindigkeit im Vergleich zu stark Lewis‐sauren Wasserstoffbrückendonoren. Durch mehrere Vergleichsexperimente, Titrationen und DFT‐Rechnungen konnte die Aktivierung des Nitrostyrols durch Chalkogenbrücken nachgewiesen werden. 相似文献
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Satoru Kuwano Takumi Suzuki Masahiro Yamanaka Ryosuke Tsutsumi Takayoshi Arai 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(30):10326-10330
Homo‐ and cross‐[4+2] cycloadditions of 2‐alkenylindoles, catalyzed by cationic halogen‐bond donors, were developed. Under mild reaction conditions, 3‐indolyl‐substituted tetrahydrocarbazole derivatives were obtained in good to excellent yields. Experimental and quantum calculation studies revealed that the electrophilic activation of 2‐alkenylindoles was achieved by C?I???π halogen bonds. 相似文献