Reactions Catalyzed by 2-Halogenated Azolium Salts: From Halogen-Bond Donors to Brønsted-Acidic Salts

Synlett ◽  
2020 ◽  
Vol 31 (08) ◽  
pp. 772-783 ◽  
Author(s):  
Yusuke Kobayashi ◽  
Yoshiji Takemoto
Keyword(s):  
Halogen Bond ◽  
Bond Cleavage ◽  
Halogen Bonding ◽  
Catalytic Reactions ◽  
Co Catalysts ◽  
Trimethylsilyl Iodide ◽  
Acidic Salt ◽  
Catalyzed Reactions ◽  
Azolium Salts ◽  
Primary Interaction

Our research group has developed a variety of organocatalysts, especially bi- and multi-functional hydrogen-bond (HB)-donor catalysts. Since 2013, we have become interested in halogen-bond (XB) interactions in organic synthesis, and we have focused on the development of organocatalysts using XBs. Although it is difficult to develop otherwise inaccessible transformations using XBs as the primary interaction, we found several unique reactions that use XB interactions in combination with co-catalysts such as trimethylsilyl iodide, Proton Sponge, and Schreiner’s thiourea. During the synthesis of various 2-iodoazolium salts that can serve as XB donors, a ‘protonated’ 2-iodoazolium salt (a Brønsted-acidic salt) was unexpectedly obtained instead of the corresponding ‘alkylated’ 2-iodoazolium salt (XB donor). The obtained Brønsted-acidic salt is unprecedentedly effective for the N-glycosylation of amides. This account summarizes our findings in this area to date.1 Introduction2 Organoiodine-Compound-Mediated Semipinacol Rearrangement via C–X Bond Cleavage3 2-Iodoazolium-Salt-Catalyzed Reactions through Halogen Bonding (XB)3.1 TMSI-Co-catalyzed Dehydroxylative Coupling of Alcohols with ­Organosilanes3.2 Base-Co-catalyzed Umpolung Alkylation of Oxindoles with an ­Iodonium(III) Ylide3.3 Thiourea-Co-catalyzed N-Glycofunctionalization of Amides3.4 Thiourea-Co-catalyzed N-α-Glycosylation of Amides4 Catalytic Reactions Using 2-Haloazolium Salts as the Brønsted Acids4.1 N-β-Glycosylation of Amides4.2 N-β-2-Deoxyglycosylation of Amides5 Conclusions

scholarly journals Adenine as a Halogen Bond Acceptor: A Combined Experimental and DFT Study

Crystals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 224 ◽  
Author(s):  
Yannick Roselló ◽  
Mónica Benito ◽  
Elies Molins ◽  
Miquel Barceló-Oliver ◽  
Antonio Frontera
Keyword(s):  
Density Functional ◽  
Halogen Bond ◽  
Lone Pair ◽  
Halogen Bonding ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Adenine Ring ◽  
Bonding Interaction ◽  
Donor Ability ◽  
Adenine Derivative

In this work, we report the cocrystallization of N9-ethyladenine with 1,2,4,5-tetrafluoro-3,6-diiodobenzene (TFDIB), a classical XB donor. As far as our knowledge extends, this is the first cocrystal reported to date where an adenine derivative acts as a halogen bond acceptor. In the solid state, each adenine ring forms two centrosymmetric H-bonded dimers: one using N1···HA6–N6 and the other N7···HB6–N6. Therefore, only N3 is available as a halogen bond acceptor that, indeed, establishes an N···I halogen bonding interaction with TFDIB. The H-bonded dimers and halogen bonds have been investigated via DFT (Density Functional Theory) calculations and the Bader’s Quantum Theory of Atoms In Molecules (QTAIM) method at the B3LYP/6-311+G* level of theory. The influence of H-bonding interactions on the lone pair donor ability of N3 has also been analyzed using the molecular electrostatic potential (MEP) surface calculations.

Double C–H Activation for the C–C bond Formation Reactions

2018 ◽  
Vol 15 (7) ◽  
pp. 882-903 ◽  
Author(s):  
Jialin Liu ◽  
Xiaoyu Xiong ◽  
Jie Chen ◽  
Yuntao Wang ◽  
Ranran Zhu ◽  
...  
Keyword(s):  
Molecular Design ◽  
Bond Cleavage ◽  
Bond Formation ◽  
Hypervalent Iodine ◽  
Coupling Reactions ◽  
Bond Forming ◽  
Direct Functionalization ◽  
Catalyzed Reactions ◽  
Medium Ring ◽  
Bond Formation Reactions

Background: Among the numerous bond-forming patterns, C–C bond formation is one of the most useful tools for building molecules for the chemical industry as well as life sciences. Recently, one of the most challenging topics is the study of the direct coupling reactions via multiple C–H bond cleavage/activation processes. A number of excellent reviews on modern C–H direct functionalization have been reported by Bergman, Bercaw, Yu and others in recent years. Among the large number of available methodologies, Pdcatalyzed reactions and hypervalent iodine reagent mediated reactions represent the most popular metal and non-metal involved transformations. However, the comprehensive summary of the comparison of metal and non-metal mediated transformations is still not available. Objective: The review focuses on comparing these two types of reactions (Pd-catalyzed reactions and hypervalent iodine reagent mediated reactions) based on the ways of forming new C–C bonds, as well as the scope and limitations on the demonstration of their synthetic applications. Conclusion: Comparing the Pd-catalyzed strategies and hypervalent iodine reagent mediated methodologies for the direct C–C bond formation from activation of C-H bonds, we clearly noticed that both strategies are powerful tools for directly obtaining the corresponding pruducts. On one hand, the hypervalent iodine reagents mediated reactions are normally under mild conditions and give the molecular diversity without the presence of transition-metal, while the Pd-catalyzed approaches have a broader scope for the wide synthetic applications. On the other hand, unlike Pd-catalyzed C-C bond formation reactions, the study towards hypervalent iodine reagent mediated methodology mainly focused on the stoichiometric amount of hypervalent iodine reagent, while few catalytic reactions have been reported. Meanwhile, hypervalent iodine strategy has been proved to be more efficient in intramolecular medium-ring construction, while there are less successful examples on C(sp3)–C(sp3) bond formation. In summary, we have demonstrated a number of selected approaches for the formation of a new C–C bond under the utilization of Pd-catalyzed reaction conditions or hyperiodine reagents. The direct activations of sp2 or sp3 hybridized C–H bonds are believed to be important strategies for the future molecular design as well as useful chemical entity synthesis.

scholarly journals An Isolable Mononuclear Palladium(I) Amido Complex

2021 ◽  
Author(s):  
jian Liu ◽  
Melissa Bollmeyer ◽  
Yujeong Kim ◽  
Dengmengfei Xiao ◽  
Samantha N. Macmillan ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Bond Cleavage ◽  
Primary Amines ◽  
Dispersion Force ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
X Ray Crystallography ◽  
Pauli Repulsion ◽  
Catalyzed Reactions ◽  
Electron Paramagnetic

Mononuclear Pd(I) species are putative intermediates in Pd-catalyzed reactions, but our knowledge about them is limited due to difficulties in accessing them. Herein, we report the isolation of a Pd(I) amido complex, [(BINAP)Pd(NHArTrip )] (BINAP = 2,2′- bis(diphenylphosphino)-1,1′-binaphthalene, ArTrip = 2,6-bis(2’,4’,6’-triisopropylphenyl)phenyl), from the reaction of (BINAP)PdCl2 with LiNHArTrip. This Pd(I) amido species has been characterized by X-ray crystallography, electron paramagnetic resonance, and multi-edge Pd Xray absorption spectroscopy. Theoretical study revealed that, while the 3-electron-2-center π interaction between Pd and N in the Pd(I) complex imposes severe Pauli repulsion in its Pd–N bond, pronounced attractive inter-ligand dispersion force aids its stabilization. In accord with its electronic features, reactions of homolytic Pd–N bond cleavage and deprotonation of primary amines are observed on the Pd(I) amido complex.

scholarly journals Computational study on the mechanism of metal-free photochemical borylation of aryl halides

2021 ◽  
Author(s):  
Chenhao Tu ◽  
Nana Ma ◽  
Qingli Xu ◽  
Wenyue Guo ◽  
Lanxin Zhou ◽  
...  
Keyword(s):  
Density Functional ◽  
Uv Light ◽  
Computational Study ◽  
Halogen Bond ◽  
Bond Cleavage ◽  
Aryl Halides ◽  
Homolytic Cleavage ◽  
Functional Theory ◽  
Aryl Radicals

C-radical borylation is an significant approach for the construction of carbon−boron bond. Photochemical borylation of aryl halides successfully applied this strategy. However, precise mechanisms, such as the generation of aryl radicals and the role of base additive(TMDAM) and water, remain controversy in these reactions. In this study, photochemical borylation of aryl halides has been researched by density functional theory (DFT) calculations. Indeed, the homolytic cleavage of the C−X bond under irradiation with UV-light is a key step for generation of aryl radicals. Nevertheless, the generation of aryl radicals may also undergo the process of single electron transfer and the heterolytic carbon-halogen bond cleavage sequence, and the latter is favorable during the reaction.

Cyclic networks of halogen-bonding interactions in molecular self-assemblies: a theoretical N—X...NversusC—X...N investigation

2017 ◽  
Vol 73 (2) ◽  
pp. 179-187
Author(s):  
Ruben D. Parra ◽  
Álvaro Castillo
Keyword(s):  
Electron Density ◽  
Self Assembly ◽  
Metal Ion ◽  
Halogen Atom ◽  
Halogen Bond ◽  
Halogen Bonding ◽  
Nbo Analysis ◽  
Binding Energies ◽  
Cyclic Network ◽  
Ability To Drive

The geometries and energetics of molecular self-assembly structures that contain a sequential network of cyclic halogen-bonding interactions are investigated theoretically. The strength of the halogen-bonding interactions is assessed by examining binding energies, electron charge transfer (NBO analysis) and electron density at halogen-bond critical points (AIM theory). Specifically, structural motifs having intramolecular N—X...N (X= Cl, Br, or I) interactions and the ability to drive molecular self-assemblyviathe same type of interactions are used to construct larger self-assemblies of up to three unit motifs. N—X...N halogen-bond cooperativity as a function of the self-assembly size, and the nature of the halogen atom is also examined. The cyclic network of the halogen-bonding interactions provides a suitable cavity rich in electron density (from the halogen atom lone pairs not involved in the halogen bonds) that can potentially bind an electron-deficient species such as a metal ion. This possibility is explored by examining the ability of the N—X...N network to bind Na+. Likewise, molecular self-assembly structures driven by the weaker C—X...N halogen-bonding interactions are investigated and the results compared with those of their N—X...N counterparts.

Au@Pd Bimetallic Nanocatalyst for Carbon–Halogen Bond Cleavage: An Old Story with New Insight into How the Activity of Pd is Influenced by Au

2018 ◽  
Vol 52 (7) ◽  
pp. 4244-4255 ◽  
Author(s):  
Rui Liu ◽  
Hui-min Chen ◽  
Li-ping Fang ◽  
Cuihong Xu ◽  
Zuoliang He ◽  
...  
Keyword(s):  
Halogen Bond ◽  
Bond Cleavage ◽  
Bimetallic Nanocatalyst ◽  
Insight Into

Cooperative halogen bonding and polarized π-stacking in the formation of coloured charge-transfer co-crystals

2018 ◽  
Vol 42 (13) ◽  
pp. 10615-10622 ◽  
Author(s):  
Chideraa I. Nwachukwu ◽  
Zachary R. Kehoe ◽  
Nathan P. Bowling ◽  
Erin D. Speetzen ◽  
Eric Bosch
Keyword(s):  
Charge Transfer ◽  
Halogen Bond ◽  
Halogen Bonding ◽  
Π Stacking

Matched electron rich halogen bond acceptors and donor have been synthesized and the halogen bonded charge transfer cocrystals characterized.

Tetradentate halogen bonding macrocyclic anion receptor inspired by the “Texas-sized” molecular box

2022 ◽  
Author(s):  
Tian Zhao ◽  
Vincent Lynch ◽  
Jonathan L. Sessler
Keyword(s):  
Click Chemistry ◽  
Halogen Bond ◽  
Halogen Bonding ◽  
Anion Receptor

Inspired by the tetracationic “Texas-sized” molecular box, a neutral analogue containing four iodotriazole halogen bond-promoting subunits (“Ibox”) was synthesized. This new macrocycle was prepared by means of azide-alkyne click chemistry....

Halogen Bonding Organocatalysis Enhanced through Intramolecular Hydrogen Bonds

2022 ◽  
Author(s):  
Asia Marie S Riel ◽  
Daniel Adam Decato ◽  
Jiyu Sun ◽  
Orion Berryman
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Halogen Bond ◽  
Direct Interaction ◽  
Halogen Bonding ◽  
Intramolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen

Recent results indicate a halogen bond donor is strengthened through direct interaction with a hydrogen bond to the electron-rich belt of the halogen. Here, this Hydrogen Bond enhanced Halogen Bond...

Sign in / Sign up

Export Citation Format

Share Document