Fluoro, Alkylsulfanyl, and Alkylsulfonyl Leaving Groups in Suzuki Cross-Coupling Reactions of Purine 2‘-Deoxynucleosides and Nucleosides†

2005 ◽  
Vol 7 (6) ◽  
pp. 1149-1151 ◽  
Author(s):  
Jiangqiong Liu ◽  
Morris J. Robins
Keyword(s):  
Cross Coupling ◽  
Coupling Reactions ◽  
Cross Coupling Reactions ◽  
Leaving Groups

scholarly journals Photo-Induced Thiolate Catalytic Activation of Inert Caryl-Hetero Bonds for Radical Borylation

2020 ◽  
Author(s):  
Shun Wang ◽  
Hua Wang ◽  
Burkhard Koenig
Keyword(s):  
Bond Activation ◽  
Reducing Power ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Reaction Conditions ◽  
Catalytic Activation ◽  
Cross Coupling Reactions ◽  
Recent Developments ◽  
Leaving Groups ◽  
Metal Catalyzed

Cross-coupling reactions are essential tools in modern synthesis of drugs, natural products and materials. The recent developments in photocatalytic radical generation have improved and expanded the classic metal-catalyzed cross coupling reactions even further. However, for sp<sup>2</sup> cross coupling reactions aryl halides or related active leaving groups, such as triflates, are required. Substituted arenes bearing strong C-X bonds remain inert to current methods. We describe now a new thiolate photocatalysis for the activation of inert substituted arenes in ipso-borylation reactions. This catalytic system exhibits strong reducing power and allows the borylation of stable C<sub>aryl</sub>−F, C<sub>aryl</sub>−O, C<sub>aryl</sub>-N and C<sub>aryl</sub>−S bonds, which are considered as chemically stable at mild reaction conditions. Our method considerably widens the available substrate scope of aryl radical precursors and we anticipate that this report will inspire new chemistry based on inert chemical bond activation.

scholarly journals Synthesis of a Bcl9 Alpha-Helix Mimetic for Inhibition of PPIs by a Combination of Electrooxidative Phenol Coupling and Pd-Catalyzed Cross Coupling

Catalysts ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 340 ◽  
Author(s):  
Martin Vareka ◽  
Benedikt Dahms ◽  
Mario Lang ◽  
Minh Hao Hoang ◽  
Melanie Trobe ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Alpha Helix ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Protein Protein Interactions ◽  
Interaction Sites ◽  
Cross Coupling Reactions ◽  
Helix Mimetics ◽  
Leaving Groups ◽  
Metal Catalyzed

Teraryl-based alpha-helix mimetics have resulted in efficient inhibitors of protein-protein interactions (PPIs). Extending the concept to even longer oligoarene systems would allow for the mimicking of even larger interaction sites. We present a highly efficient synthetic modular access to quateraryl alpha-helix mimetics, in which, at first, two phenols undergo electrooxidative dehydrogenative cross-coupling. The resulting 4,4′-biphenol is then activated by conversion to nonaflates, which serve as leaving groups for iterative Pd-catalyzed Suzuki-cross-coupling reactions with suitably substituted pyridine boronic acids. This work, for the first time, demonstrates the synthetic efficiency of using both electroorganic as well as transition-metal catalyzed cross-coupling in the assembly of oligoarene structures.

scholarly journals Photo-Induced Thiolate Catalytic Activation of Inert Caryl-Hetero Bonds for Radical Borylation

2020 ◽  
Author(s):  
Shun Wang ◽  
Hua Wang ◽  
Burkhard Koenig
Keyword(s):  
Bond Activation ◽  
Reducing Power ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Reaction Conditions ◽  
Catalytic Activation ◽  
Cross Coupling Reactions ◽  
Recent Developments ◽  
Leaving Groups ◽  
Metal Catalyzed

Cross-coupling reactions are essential tools in modern synthesis of drugs, natural products and materials. The recent developments in photocatalytic radical generation have improved and expanded the classic metal-catalyzed cross coupling reactions even further. However, for sp<sup>2</sup> cross coupling reactions aryl halides or related active leaving groups, such as triflates, are required. Substituted arenes bearing strong C-X bonds remain inert to current methods. We describe now a new thiolate photocatalysis for the activation of inert substituted arenes in ipso-borylation reactions. This catalytic system exhibits strong reducing power and allows the borylation of stable C<sub>aryl</sub>−F, C<sub>aryl</sub>−O, C<sub>aryl</sub>-N and C<sub>aryl</sub>−S bonds, which are considered as chemically stable at mild reaction conditions. Our method considerably widens the available substrate scope of aryl radical precursors and we anticipate that this report will inspire new chemistry based on inert chemical bond activation.

Dual Nickel/Palladium-Catalyzed Reductive Cross-Coupling Reactions Between Two Phenol Derivatives

2020 ◽  
Author(s):  
Baojian Xiong ◽  
Yue Li ◽  
Yin Wei ◽  
Søren Kramer ◽  
Zhong Lian
Keyword(s):  
Functional Group ◽  
Low Cost ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Phenol Derivatives ◽  
Cross Coupling Reactions ◽  
Palladium Catalyzed ◽  
One Step ◽  
Aryl Tosylates ◽  
Low Sensitivity

Cross-coupling between substrates that can be easily derived from phenols is highly attractive due to the abundance and low cost of phenols. Here, we report a dual nickel/palladium-catalyzed reductive cross-coupling between aryl tosylates and aryl triflates; both substrates can be accessed in just one step from readily available phenols. The reaction has a broad functional group tolerance and substrate scope (>60 examples). Furthermore, it displays low sensitivity to steric effects demonstrated by the synthesis of a 2,2’disubstituted biaryl and a fully substituted aryl product. The widespread presence of phenols in natural products and pharmaceuticals allow for straightforward late-stage functionalization, illustrated with examples such as Ezetimibe and tyrosine. NMR spectroscopy and DFT calculations indicate that the nickel catalyst is responsible for activating the aryl triflate, while the palladium catalyst preferentially reacts with the aryl tosylate.

An Iron-Based Catalyst Enables The Enantioconvergent Synthesis of Chiral 1,1-Diarylalkanes Through a Suzuki-Miyaura Cross-Coupling Reaction

2020 ◽  
Author(s):  
Chet Tyrol ◽  
Nang Yone ◽  
Connor Gallin ◽  
Jeffery Byers
Keyword(s):  
Coupling Reaction ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Radical Intermediates ◽  
Cross Coupling Reactions ◽  
Cross Coupling Reaction ◽  
Boronic Esters ◽  
Carbon Centered Radical ◽  
Iron Based ◽  
High Yields

By using an iron-based catalyst, access to enantioenriched 1,1-diarylakanes was enabled through an enantioselective Suzuki-Miyaura crosscoupling reaction. The combination of a chiral cyanobis(oxazoline) ligand framework and 1,3,5-trimethoxybenzene additive were essential to afford high yields and enantioselectivities in cross-coupling reactions between unactivated aryl boronic esters and a variety of benzylic chlorides, including challenging ortho-substituted benzylic chloride substrates. Mechanistic investigations implicate a stereoconvergent pathway involving carbon-centered radical intermediates.

Phosphino-Triazole Ligands for Palladium-Catalysed Cross-Coupling

2018 ◽  
Author(s):  
Yiming Zhao ◽  
Huy van Nguyen ◽  
Louise Male ◽  
Philip Craven ◽  
Benjamin R. Buckley ◽  
...  
Keyword(s):  
Drug Discovery ◽  
Cross Coupling ◽  
Product Formation ◽  
Coupling Reactions ◽  
Volume Determination ◽  
Online Tool ◽  
Triazole Derivatives ◽  
Cross Coupling Reactions ◽  
Modelling Approaches

<div>Twelve 1,5-disubtituted and fourteen 5-substituted 1,2,3-triazole derivatives bearing diaryl or dialkyl phosphines at the 5-position were synthesised and used as ligands for palladium-catalysed Suzuki-Miyaura cross-coupling reactions. Bulky substrates were tested, and lead-like product formation was demonstrated. The online tool SambVca 2.0 was used to assess steric parameters of ligands and preliminary buried volume determination using XRD obtained data in a small number of cases proved to be informative. Two modelling approaches were compared for the determination of</div><div>the buried volume of ligands where XRD data was not available. An approach with imposed steric restrictions was found to be superior in leading to buried volume determinations that closely correlate with observed reaction conversions. The online tool LLAMA was used to determine lead-likeness of potential Suzuki-Miyaura cross-coupling products, from which ten of the most lead-like were successfully synthesised. Thus, confirming these readily accessible triazole-containing phosphines as highly suitable ligands for reaction screening and optimisation in drug discovery campaigns.</div>

A Revised Modular Approach to D8-THC and Derivatives Through Late-Stage Suzuki-Miyaura Cross-Coupling Reactions

2019 ◽  
Author(s):  
Victor Bloemendal ◽  
Floris P. J. T. Rutjes ◽  
Thomas J. Boltje ◽  
Daan Sondag ◽  
Hidde Elferink ◽  
...  
Keyword(s):  
Biological Activity ◽  
Late Stage ◽  
Medicinal Chemistry ◽  
Cross Coupling ◽  
Modular Approach ◽  
Coupling Reactions ◽  
One Pot ◽  
Biologically Relevant ◽  
Cross Coupling Reactions ◽  
Chemistry Research

<p>In this manuscript we describe a modular pathway to synthesize biologically relevant (–)-<i>trans</i>-Δ<sup>8</sup>-THC derivatives, which can be used to modulate the pharmacologically important CB<sub>1</sub> and CB<sub>2</sub> receptors. This pathway involves a one-pot Friedel-Crafts alkylation/cyclization protocol, followed by Suzuki-Miyaura cross-coupling reactions and gives rise to a series of new Δ<sup>8</sup>-THC derivatives. In addition, we demonstrate using extensive NMR evidence that similar halide-substituted Friedel-Crafts alkylation/cyclization products in previous articles were wrongly assigned as the para-isomers, which also has consequence for the assignment of the subsequent cross-coupled products and interpretation of their biological activity. </p> <p>Considering the importance of the availability of THC derivatives in medicinal chemistry research and the fact that previously synthesized compounds were wrongly assigned, we feel this research is describing a straightforward pathway into new cannabinoids.</p>

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