scholarly journals Chemodivergent Organolanthanide Catalyzed C-H a-Mono-1 Borylation of Azines

2021 ◽  
Author(s):  
Jacob O. Rothbaum ◽  
Alessandro Motta ◽  
Yosi Kratish ◽  
Tobin Marks
Keyword(s):  
Metal Ion ◽  
Lone Pair ◽  
Cross Coupling ◽  
Steric Repulsion ◽  
Coupling Reactions ◽  
Bond Forming ◽  
Cross Coupling Reactions ◽  
Modern Chemical ◽  
Earth Abundant ◽  
Nitrogen Lone Pair

C-H activation and functionalization of pyridinoid azines is a key transformation forthe synthesis of many natural products, pharmaceuticals, and materials. Reflecting the azinyl nitrogen lone-pair steric repulsion, tendency to irreversibly bind to metal ion catalysts, and the electron-deficient nature of pyridine, C-H functionalization at the important a-position remains challenging. Thus, the development of earth abundant catalysts for the a-selective mono-functionalization of azines is a crucial hurdle for modern chemical synthesis. Here, the selective organolanthanide catalyzed a-mono-borylation of a diverse series of pyridines is reported, affording a valuable precursor for cross-coupling reactions. Experimental and theoretical mechanistic evidence support the formation of a C-H activated η2-lanthanide-azine complex, followed by intermolecular a-mono-borylation via σ-bond metathesis. Notably, varying the lanthanide identity and substrate electronics promotes chemodivergence of the catalytic selectivity: smaller/more electrophilic lanthanide3+ ions and electron-rich substrates favor selective a-C-H functionalization, whereas larger/less electrophilic lanthanide3+ 1 ions and electron poor substrates favor selective B-N bond-forming 1,2-dearomatization. Such organolanthanide series catalytic chemodivergence is, to our knowledge, unprecedented.

scholarly journals Iodination of carbohydrate-derived 1,2-oxazines to enantiopure 5-iodo-3,6-dihydro-2H-1,2-oxazines and subsequent palladium-catalyzed cross-coupling reactions

2016 ◽  
Vol 12 ◽  
pp. 2898-2905 ◽  
Author(s):  
Michal Medvecký ◽  
Igor Linder ◽  
Luise Schefzig ◽  
Hans-Ulrich Reissig ◽  
Reinhold Zimmer
Keyword(s):  
Click Reaction ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
High Efficacy ◽  
Carbon Bond ◽  
Bond Forming ◽  
Cross Coupling Reactions ◽  
Carbon Carbon Bond ◽  
Palladium Catalyzed ◽  
Oxazine Derivatives

Iodination of carbohydrate-derived 3,6-dihydro-2H-1,2-oxazines of type 3 using iodine and pyridine in DMF furnished 5-iodo-substituted 1,2-oxazine derivatives 4 with high efficacy. The alkenyl iodide moiety of 1,2-oxazine derivatives syn-4 and anti-4 was subsequently exploited for the introduction of new functionalities at the C-5 position by applying palladium-catalyzed carbon–carbon bond-forming reactions such as Sonogashira, Heck, or Suzuki coupling reactions as well as a cyanation reaction. These cross-coupling reactions led to a series of 5-alkynyl-, 5-alkenyl-, 5-aryl- and 5-cyano-substituted 1,2-oxazine derivatives being of considerable interest for further synthetic elaborations. This was exemplarily demonstrated by the hydrogenation of syn-21 and anti-24 and by a click reaction of a 5-alkynyl-substituted precursor.

Cu(III)-Mediated Aerobic Oxidations

Synthesis ◽  
2018 ◽  
Vol 51 (02) ◽  
pp. 334-358 ◽  
Author(s):  
Jean-Philip Lumb ◽  
Kenneth Esguerra
Keyword(s):  
Cross Coupling ◽  
Coupling Reactions ◽  
Oxidation Reactions ◽  
General Introduction ◽  
Model Complexes ◽  
Bond Forming ◽  
Cross Coupling Reactions ◽  
Carbon Carbon Bond ◽  
Bond Forming Reactions ◽  
Type 3

CuIII species have been invoked in many copper-catalyzed transformations including cross-coupling reactions and oxidation reactions. In this review, we will discuss seminal discoveries that have advanced our understanding of the CuI/CuIII redox cycle in the context of C–C and C–heteroatom aerobic cross-coupling reactions, as well as C–H oxidation reactions mediated by CuIII–dioxygen adducts.1 General Introduction2 Early Examples of CuIII Complexes3 Aerobic CuIII-Mediated Carbon–Heteroatom Bond-Forming Reactions4 Aerobic CuIII-Mediated Carbon–Carbon Bond-Forming Reactions5 Bioinorganic Studies of CuIII Complexes from CuI and O2 5.1 O2 Activation5.2 Biomimetic CuIII Complexes from CuI and Dioxygen5.2.1 Type-3 Copper Enzymes and Dinuclear Cu Model Complexes5.2.2 Particulate Methane Monooxygenase and Di- and Trinuclear Cu Model Complexes5.2.3 Dopamine–β-Monooxygenase and Mononuclear Cu Model Complexes6 Conclusion

scholarly journals Perfluorinated phosphine and hybrid P–O ligands for Pd catalysed C–C bond forming reactions in solution and on Teflon supports

RSC Advances ◽  
2019 ◽  
Vol 9 (50) ◽  
pp. 28936-28945
Author(s):  
Farzana Begum ◽  
Muhammad Ikram ◽  
Brendan Twamley ◽  
Robert J. Baker
Keyword(s):  
Cross Coupling ◽  
Phosphine Ligands ◽  
Coupling Reactions ◽  
Bond Forming ◽  
Cross Coupling Reactions ◽  
Bond Forming Reactions

Phosphine ligands containing a perfluorous ponytail can be sorbed onto Teflon tape and used as ligands for C–C cross coupling reactions with little leaching.

scholarly journals Heterogeneous catalysis by ultra-small bimetallic nanoparticles surpassing homogeneous catalysis for carbon–carbon bond forming reactions

Nanoscale ◽  
2020 ◽  
Vol 12 (37) ◽  
pp. 19191-19202 ◽  
Author(s):  
Nazgol Norouzi ◽  
Mrinmoy K. Das ◽  
Alexander J. Richard ◽  
Amr A. Ibrahim ◽  
Hani M. El-Kaderi ◽  
...  
Keyword(s):  
Heterogeneous Catalysis ◽  
Homogeneous Catalysis ◽  
Bimetallic Catalysts ◽  
Fumed Silica ◽  
Bimetallic Nanoparticles ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Bond Forming ◽  
Cross Coupling Reactions ◽  
Carbon Carbon Bond

Heterogeneous Pd-based bimetallic catalysts supported on fumed silica with high activity and selectivity matching those of homogeneous catalysts have been developed for carbon–carbon cross-coupling reactions.

Mechanism of the t-BuOM (M = K, Na, Li)/DMEDA-Mediated Direct C–H Arylation of Benzene: A Computational Study

Synthesis ◽  
2020 ◽  
Vol 52 (19) ◽  
pp. 2883-2891
Author(s):  
Mahendra Patil
Keyword(s):  
Metal Ion ◽  
Computational Study ◽  
Lone Pair ◽  
Organic Additive ◽  
Radical Addition ◽  
Elementary Step ◽  
Coupling Reactions ◽  
The Past ◽  
Cross Coupling Reactions ◽  
Metal Catalyzed

Over the past ten years, a combination of organic additive and t-BuOK/t-BuONa has been successfully used for the direct C–H arylation of arenes. Conceptually different from transition-metal-catalyzed cross-coupling reactions, these t-BuOK-mediated reactions have raised significant curiosity among organic chemists. Herein, a systematic computational study of each elementary step of the t-BuOM (M = K, Na, Li)/N 1,N 2-dimethylethane-1,2-diamine (DMEDA) mediated direct C–H arylation of benzene is detailed. The presented mechanistic proposal relies on the complexation and reaction of t-BuOM with DMEDA (additive), which leads to the formation of different complexes such as SED(M+)…PhI. These complexes mainly involve coordination of the metal ion (from t-BuOM) to the additive and iodobenzene via stabilizing cation–lone pair and cation–π interactions. Such complexation of a metal ion to an additive and iodobenzene not only ensures facile electron transfer to iodobenzene but also provides a lowest energy pathway for the subsequent radical addition and deprotonation step.

Chromium-Catalyzed Cross-Coupling Reactions by Selective Activation of Chemically Inert Aromatic C−O, C−N and C−H Bonds

Synlett ◽  
2021 ◽  
Author(s):  
Xuefeng Cong ◽  
Xiaoming Zeng
Keyword(s):  
Precious Metals ◽  
Cross Coupling ◽  
High Spin State ◽  
Cost Effective ◽  
Coupling Reactions ◽  
Nickel Iron ◽  
Effective Strategies ◽  
Cross Coupling Reactions ◽  
Earth Abundant ◽  
Metal Catalyzed

Transition-metal-catalyzed cross-coupling has appeared as one of powerful and useful tools in the formation of C–C and C–heteroatom bonds. Given that the resource of precious metals on earth is shortage, the use of earth-abundant metals as catalysts in developing cost-effective strategies of cross-coupling is one of trends to synthetic chemistry. Compared with the achievements using first-row metal catalysis of nickel, iron, cobalt, and even manganese, the group 6 metal chromium has rarely been used in promoting cross-coupling. This perspective will cover recent advances in Cr-catalyzed cross-coupling reactions by the transformations of chemically inert C(aryl)–O, C(aryl)–N and C(aryl)–H bonds, offering selective strategies for molecule construction. The ability of low-valent Cr with a high-spin state involving in the process of two-electron oxidative addition will be highlighted, which is different with the mechanism by single-electron-transfer that is traditionally proposed in chromium-mediated transformations. 1 Introduction 2 Cr-Catalyzed Kumada Coupling of Unactivated C(aryl)−O and C(aryl)−N Bonds 3 Cr-Catalyzed Reductive Cross-Coupling between Two Unactivated C(aryl)–Heteroatom Bonds 4 Cr-Catalyzed Functionalization of Unactivated C(aryl)–H Bonds 5 Conclusion and Outlook

Iron-Catalyzed C(sp2)–C(sp3) Cross-Coupling Reactions of Di(hetero)arylmanganese Reagents and Primary and Secondary Alkyl Halides

Synlett ◽  
2017 ◽  
Vol 29 (01) ◽  
pp. 65-70 ◽  
Author(s):  
Paul Knochel ◽  
Maximilian Hofmayer ◽  
Jeffrey Hammann ◽  
Gérard Cahiez
Keyword(s):  
Cross Coupling ◽  
Alkyl Halides ◽  
Coupling Reactions ◽  
Bond Forming ◽  
Cross Coupling Reactions ◽  
Bond Forming Reactions

An iron-catalyzed cross-coupling between di(hetero)arylmanganese reagents and primary and secondary alkyl halides is reported. No rearrangement of secondary alkyl halides to unbranched products was observed in these C–C bond-forming reactions.

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