scholarly journals Heterobiaryl synthesis by contractive C–C coupling via P(V) intermediates

Science ◽  
2018 ◽  
Vol 362 (6416) ◽  
pp. 799-804 ◽  
Author(s):  
Michael C. Hilton ◽  
Xuan Zhang ◽  
Benjamin T. Boyle ◽  
Juan V. Alegre-Requena ◽  
Robert S. Paton ◽  
...  
Keyword(s):  
Cross Coupling ◽  
The Other ◽  
Coupling Reactions ◽  
Mechanistic Studies ◽  
Alternative Approach ◽  
Metal Catalyzed ◽  
Polar Functional Groups ◽  
Pharmacological Function ◽  
Complex Drug ◽  
Acidic Alcohol

Heterobiaryls composed of pyridine and diazine rings are key components of pharmaceuticals and are often central to pharmacological function. We present an alternative approach to metal-catalyzed cross-coupling to make heterobiaryls using contractive phosphorus C–C couplings, also termed phosphorus ligand coupling reactions. The process starts by regioselective phosphorus substitution of the C–H bonds para to nitrogen in two successive heterocycles; ligand coupling is then triggered via acidic alcohol solutions to form the heterobiaryl bond. Mechanistic studies imply that ligand coupling is an asynchronous process involving migration of one heterocycle to the ipso position of the other around a central pentacoordinate P(V) atom. The strategy can be applied to complex drug-like molecules containing multiple reactive sites and polar functional groups, and also enables convergent coupling of drug fragments and late-stage heteroarylation of pharmaceuticals.

scholarly journals Non-Symmetrical Bis-Azine Biaryls from Chloroazines: A Strategy Using Phosphorus Ligand-Coupling

2019 ◽  
Author(s):  
Benjamin T. Boyle ◽  
Michael C. Hilton ◽  
Andrew McNally
Keyword(s):  
Cross Coupling ◽  
Coupling Reactions ◽  
One Pot ◽  
Cross Coupling Reactions ◽  
Alternative Approach ◽  
Metal Catalyzed ◽  
Traditional Approaches ◽  
Coupling Partner ◽  
Coupling Sequence

Distinct approaches to synthesize bis-azine biaryls are in demand as these compounds have multiple applications in the chemical sciences and are challenging targets for metal-catalyzed cross-coupling reactions. Most approaches focus on developing new reagents as the formal nucleophilic coupling partner that can function in metal-catalyzed processes. We present an alternative approach using pyridine and diazine phosphines as nucleophilic partners and chloroazines where the heterobiaryl bond is formed via a tandem S<sub><i>N</i></sub>Ar-phosphorus ligand-coupling sequence. The heteroaryl phosphines are prepared from chloroazines and are bench stable solids. Using this strategy, a range of bis-azine biaryls can be formed from abundant chloroazines that would be challenging using traditional approaches and a one-pot cross-electrophile coupling of two chloroazines is feasible.

scholarly journals Non-Symmetrical Bis-Azine Biaryls from Chloroazines: A Strategy Using Phosphorus Ligand-Coupling

2019 ◽  
Author(s):  
Benjamin T. Boyle ◽  
Michael C. Hilton ◽  
Andrew McNally
Keyword(s):  
Cross Coupling ◽  
Coupling Reactions ◽  
One Pot ◽  
Cross Coupling Reactions ◽  
Alternative Approach ◽  
Metal Catalyzed ◽  
Traditional Approaches ◽  
Coupling Partner ◽  
Coupling Sequence

Distinct approaches to synthesize bis-azine biaryls are in demand as these compounds have multiple applications in the chemical sciences and are challenging targets for metal-catalyzed cross-coupling reactions. Most approaches focus on developing new reagents as the formal nucleophilic coupling partner that can function in metal-catalyzed processes. We present an alternative approach using pyridine and diazine phosphines as nucleophilic partners and chloroazines where the heterobiaryl bond is formed via a tandem S<sub><i>N</i></sub>Ar-phosphorus ligand-coupling sequence. The heteroaryl phosphines are prepared from chloroazines and are bench stable solids. Using this strategy, a range of bis-azine biaryls can be formed from abundant chloroazines that would be challenging using traditional approaches and a one-pot cross-electrophile coupling of two chloroazines is feasible.

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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