scholarly journals Recent Advances in the Synthesis of Benzimidazole Derivatives from the Oxidative Coupling of Primary Amines

Synthesis ◽  
2017 ◽  
Vol 50 (02) ◽  
pp. 241-253 ◽  
Author(s):  
Martine Largeron ◽  
Khac Nguyen
Keyword(s):  
Oxidative Coupling ◽  
Environmentally Benign ◽  
Primary Amines ◽  
Benzimidazole Derivatives ◽  
Coupling Reactions ◽  
Cross Coupling Reactions ◽  
Different Types ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Molecular Framework

Benzimidazole belongs to the top five most commonly used five-membered aromatic nitrogen heterocycles among U.S. FDA approved pharmaceuticals. Over the last few years, a large number of improved synthetic strategies have been developed to construct the benz­imidazole molecular framework under environmentally benign conditions. This review focuses on the use of primary amines as readily available substrates for the synthesis of benzimidazole derivatives through different types of oxidative cross-coupling reactions.1 Introduction2 Catalyst-Free Oxidative Coupling of Primary Amines3 Catalytic Oxidative Coupling of Primary Amines3.1 Metal-Catalyzed Reactions3.2 Metal-Free Catalyzed Reactions3.3 Bioinspired Catalyzed Reactions4 Conclusion

Monodentate Trialkylphosphines: Privileged Ligands in Metal-catalyzed Crosscoupling Reactions

2020 ◽  
Vol 24 (3) ◽  
pp. 231-264 ◽  
Author(s):  
Kevin H. Shaughnessy
Keyword(s):  
Transition Metal ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Cross Coupling Reactions ◽  
Aryl Bromides ◽  
Wide Range ◽  
Sterically Demanding ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed

Phosphines are widely used ligands in transition metal-catalyzed reactions. Arylphosphines, such as triphenylphosphine, were among the first phosphines to show broad utility in catalysis. Beginning in the late 1990s, sterically demanding and electronrich trialkylphosphines began to receive attention as supporting ligands. These ligands were found to be particularly effective at promoting oxidative addition in cross-coupling of aryl halides. With electron-rich, sterically demanding ligands, such as tri-tertbutylphosphine, coupling of aryl bromides could be achieved at room temperature. More importantly, the less reactive, but more broadly available, aryl chlorides became accessible substrates. Tri-tert-butylphosphine has become a privileged ligand that has found application in a wide range of late transition-metal catalyzed coupling reactions. This success has led to the use of numerous monodentate trialkylphosphines in cross-coupling reactions. This review will discuss the general properties and features of monodentate trialkylphosphines and their application in cross-coupling reactions of C–X and C–H bonds.

scholarly journals Copper’s rapid ascent in visible-light photoredox catalysis

Science ◽  
2019 ◽  
Vol 364 (6439) ◽  
pp. eaav9713 ◽  
Author(s):  
Asik Hossain ◽  
Aditya Bhattacharyya ◽  
Oliver Reiser
Keyword(s):  
Visible Light ◽  
Organic Dyes ◽  
Low Cost ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Photoredox Catalysis ◽  
Cross Coupling Reactions ◽  
Rapid Ascent ◽  
Catalyzed Reactions ◽  
Metal Catalyzed

Visible-light photoredox catalysis offers a distinct activation mode complementary to thermal transition metal catalyzed reactions. The vast majority of photoredox processes capitalizes on precious metal ruthenium(II) or iridium(III) complexes that serve as single-electron reductants or oxidants in their photoexcited states. As a low-cost alternative, organic dyes are also frequently used but in general suffer from lower photostability. Copper-based photocatalysts are rapidly emerging, offering not only economic and ecological advantages but also otherwise inaccessible inner-sphere mechanisms, which have been successfully applied to challenging transformations. Moreover, the combination of conventional photocatalysts with copper(I) or copper(II) salts has emerged as an efficient dual catalytic system for cross-coupling reactions.

Transition-metal-catalyzed reactions of carbon-heteroatom bond formation by substitution and addition processes

2005 ◽  
Vol 77 (12) ◽  
pp. 2021-2027 ◽  
Author(s):  
Irina P. Beletskaya
Keyword(s):  
Transition Metal ◽  
Triple Bond ◽  
Bond Formation ◽  
Cross Coupling ◽  
Addition Reactions ◽  
Coupling Reactions ◽  
Cross Coupling Reactions ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed

Two types of transition-metal-catalyzed cross-coupling reactions, which both lead to the formation of carbon-heteroatom bonds, are considered: RX + E-H and E-X + RM. The potential of addition reactions of E-H or E-E to double or triple bond in C-E bond formation is also demonstrated.

scholarly journals Metal-Catalyzed Cross-Coupling Reactions on Azaindole Synthesis and Functionalization

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2673 ◽  
Author(s):  
A. Santos ◽  
Ana Mortinho ◽  
M. Marques
Keyword(s):  
Drug Discovery ◽  
Scientific Community ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Cross Coupling Reactions ◽  
Synthetic Methodologies ◽  
Catalyzed Reactions ◽  
Metal Catalyzed

Azaindoles are rare in nature but extremely attractive for drug discovery programs. Azaindoles can be obtained by diverse methods, including those involving metal-catalyzed reactions. This important core has been fascinating the scientific community due to their challenging synthesis and relevant bioactivity. This paper highlights the diverse synthetic methodologies developed to date involving metal-catalyzed reaction to attain azaindoles and its functionalization.

Pd-Catalyzed Functionalization of Aryl Amines on a Soluble Polymer Support

Synlett ◽  
2020 ◽  
Vol 31 (20) ◽  
pp. 2027-2034
Author(s):  
M. Manuel B. Marques ◽  
A. Sofia Santos
Keyword(s):  
Polymer Support ◽  
Coupling Reactions ◽  
Proof Of Concept ◽  
Heck Reactions ◽  
Soluble Polymer ◽  
Cross Coupling Reactions ◽  
Aryl Amines ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Privileged Structures

AbstractHerein we report the use of a soluble polymer support PEG-2000 on Pd-catalyzed reactions to improve the functionalization of aromatic amines and the synthesis of N-heterocycles. Compatibility of metal-catalyzed reactions for assembling privileged structures such as functionalized anilines were studied. PEG-supported anilines were found to be suitable substrates for Pd-catalyzed N-arylation, Sonogashira and Heck reactions. PEGylated substrates were prepared in yields up to 94%. This work consists on a proof of concept on the use of PEGylated anilines on Pd-catalyzed cross-coupling reactions. Indole core was attained in 82% and 62% yields, via two different routes.

scholarly journals Synthesis of Computationally Designed 2,5(6)-Benzimidazole Derivatives via Pd-Catalyzed Reactions for Potential E. coli DNA Gyrase B Inhibition

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1326
Author(s):  
Rafael T. Aroso ◽  
Rita C. Guedes ◽  
Mariette M. Pereira
Keyword(s):  
Pharmacophore Model ◽  
Dna Gyrase ◽  
Inhibitory Effect ◽  
Docking Studies ◽  
Benzimidazole Derivatives ◽  
Coupling Reactions ◽  
Hydrogen Bond Donor ◽  
Cross Coupling Reactions ◽  
Palladium Catalyzed ◽  
Catalyzed Reactions

A pharmacophore model for inhibitors of Escherichia coli’s DNA Gyrase B was developed, using computer-aided drug design. Subsequently, docking studies showed that 2,5(6)-substituted benzimidazole derivatives are promising molecules, as they possess key hydrogen bond donor/acceptor groups for an efficient interaction with this bacterial target. Furthermore, 5(6)-bromo-2-(2-nitrophenyl)-1H-benzimidazole, selected as a core molecule, was prepared on a multi-gram scale through condensation of 4-bromo-1,2-diaminobenzene with 2-nitrobenzaldehyde using a sustainable approach. The challenging functionalization of the 5(6)-position was carried out via palladium-catalyzed Suzuki–Miyaura and Buchwald-Hartwig amination cross-coupling reactions between N-protected-5-bromo-2-nitrophenyl-benzimidazole and aryl boronic acids or sulfonylanilines, with yields up to 81%. The final designed molecules (2-(aminophen-2-yl)-5(6)-substituted-1H-benzimidazoles), which encompass the appropriate functional groups in the 5(6)-position according to the pharmacophore model, were obtained in yields up to 91% after acid-mediated N-boc deprotection followed by Pd-catalyzed hydrogenation. These groups are predicted to favor interactions with DNA gyrase B residues Asn46, Asp73, and Asp173, aiming to promote an inhibitory effect.

Synthesis of Marine Polyacetylenes Callyberynes A−C by Transition-Metal-Catalyzed Cross-Coupling Reactions to sp Centers

2006 ◽  
Vol 71 (7) ◽  
pp. 2802-2810 ◽  
Author(s):  
Susana López ◽  
Francisco Fernández-Trillo ◽  
Pilar Midón ◽  
Luis Castedo ◽  
Carlos Saá
Keyword(s):  
Transition Metal ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Cross Coupling Reactions ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

scholarly journals Protecting group-free, selective cross-coupling of alkyltrifluoroborates with borylated aryl bromides via photoredox/nickel dual catalysis

2015 ◽  
Vol 112 (39) ◽  
pp. 12026-12029 ◽  
Author(s):  
Yohei Yamashita ◽  
John C. Tellis ◽  
Gary A. Molander
Keyword(s):  
Small Molecules ◽  
Functional Group ◽  
Cross Coupling ◽  
Differential Protection ◽  
Coupling Reactions ◽  
Protecting Group ◽  
Cross Coupling Reactions ◽  
Aryl Bromides ◽  
Rapid Construction ◽  
Metal Catalyzed

Orthogonal reactivity modes offer substantial opportunities for rapid construction of complex small molecules. However, most strategies for imparting orthogonality to cross-coupling reactions rely on differential protection of reactive sites, greatly reducing both atom and step economies. Reported here is a strategy for orthogonal cross-coupling wherein a mechanistically distinct activation mode for transmetalation of sp3-hybridized organoboron reagents enables C-C bond formation in the presence of various protected and unprotected sp2-hybridized organoborons. This manifold has the potential for broad application, because orthogonality is inherent to the activation mode itself. The diversification potential of this platform is shown in the rapid elaboration of a trifunctional lynchpin through various transition metal-catalyzed processes without nonproductive deprotection or functional group manipulation steps.

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