scholarly journals Mixed-Halide Triphenyl Methyl Radicals for Site-Selective Functionalization and Polymerization

2021 ◽  
Author(s):  
Lisa Chen ◽  
Mona Arnold ◽  
Rémi Blinder ◽  
Fedor Jelezko ◽  
Alexander Kuehne
Keyword(s):  
Cross Coupling ◽  
Open Shell ◽  
Quantum Yields ◽  
Coupling Reactions ◽  
Methyl Radicals ◽  
Cross Coupling Reactions ◽  
Donor Acceptor ◽  
Metal Catalyzed ◽  
Derivatives Of ◽  
Acceptor Molecules

<p>Derivatives of the stable, luminescent tris-2,4,6-trichlorophenylmethyl (TTM) radical exhibit unique doublet spin properties that are of interest for applications in optoelectronics, spintronics, and energy storage. However, the synthesis and variety of TTM-type donor-acceptor molecules with high quantum yields are limited by the symmetric chloride decoration and poor reactivity of chlorides in metal-catalyzed C-C cross-coupling reactions. Therefore, only few donor-acceptor molecules have been successfully coupled to the TTM radical motif. Here, we present a synthetic pathway to obtain mixed-halide derivatives of TTM, partly carrying bromo- instead of chloro-substituents, leading to improved reactivity and enabling site-specific cross-coupling reactions. These highly stable mixed-halide triphenyl methyl radicals represent a powerful tool to obtain complex, and so far inaccessible open-shell small molecules, as well as polymers.</p>

scholarly journals Mixed-Halide Triphenyl Methyl Radicals for Site-Selective Functionalization and Polymerization

2021 ◽  
Author(s):  
Lisa Chen ◽  
Mona Arnold ◽  
Rémi Blinder ◽  
Fedor Jelezko ◽  
Alexander Kuehne
Keyword(s):  
Cross Coupling ◽  
Open Shell ◽  
Quantum Yields ◽  
Coupling Reactions ◽  
Methyl Radicals ◽  
Cross Coupling Reactions ◽  
Donor Acceptor ◽  
Metal Catalyzed ◽  
Derivatives Of ◽  
Acceptor Molecules

<p>Derivatives of the stable, luminescent tris-2,4,6-trichlorophenylmethyl (TTM) radical exhibit unique doublet spin properties that are of interest for applications in optoelectronics, spintronics, and energy storage. However, the synthesis and variety of TTM-type donor-acceptor molecules with high quantum yields are limited by the symmetric chloride decoration and poor reactivity of chlorides in metal-catalyzed C-C cross-coupling reactions. Therefore, only few donor-acceptor molecules have been successfully coupled to the TTM radical motif. Here, we present a synthetic pathway to obtain mixed-halide derivatives of TTM, partly carrying bromo- instead of chloro-substituents, leading to improved reactivity and enabling site-specific cross-coupling reactions. These highly stable mixed-halide triphenyl methyl radicals represent a powerful tool to obtain complex, and so far inaccessible open-shell small molecules, as well as polymers.</p>

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.

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.

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.

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