1.8 Nitrogen-Centered Radicals

2021 ◽  
Author(s):  
X.-L. Lu ◽  
B. Wang ◽  
S. Chiba
Keyword(s):  
Functional Materials ◽  
Synthetic Methods ◽  
Pharmaceutical Drugs ◽  
Forming Process ◽  
Efficient Manner ◽  
Bond Forming ◽  
Synthetic Methodologies ◽  
Metal Catalyzed ◽  
User Friendly ◽  
Nitrogen Containing Compounds

AbstractNitrogen-containing compounds are prevalent in the key components of various functional materials and compounds such as pharmaceutical drugs. Therefore, it is extremely important to develop versatile synthetic methodologies capable of constructing C—N bonds in an efficient manner under milder reaction conditions. Apart from common ionic C—N bond-forming reactions (i.e., nucleophilic and electrophilic amination, as well as transition-metal-catalyzed C—N cross-coupling processes), leveraging of nitrogen-centered radicals for C—N bond-forming process has created another dimension to the modern synthesis of nitrogen-containing compounds. In particular, recent development of novel catalytic strategies and the design of new nitrogen-radical precursors have rendered their generation and use for C—N bond formation more practical and user-friendly for synthesis of wider array of nitrogen-containing compounds of potential use. This chapter highlights the latest developments in synthetic methods for C—N bond construction using nitrogen-centered radicals by showing selected reactions, mostly reported in the last five years, based on their structural and reactivity features as well as the method of radical generation.

scholarly journals Recent Advances in One-Pot Modular Synthesis of 2-Quinolones

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5450
Author(s):  
Wan Pyo Hong ◽  
Inji Shin ◽  
Hee Nam Lim
Keyword(s):  
Reaction Mechanism ◽  
Small Molecules ◽  
Functional Materials ◽  
Synthetic Methods ◽  
Microwave Irradiation Method ◽  
One Pot ◽  
Bond Forming ◽  
Chemical Structures ◽  
The Core ◽  
Modular Synthesis

It is known that 2-quinolones are broadly applicable chemical structures in medicinal and agrochemical research as well as various functional materials. A number of current publications about their synthesis and their applications emphasize the importance of these small molecules. The early synthetic chemistry originated from the same principle of the classical Friedländer and Knorr procedures for the preparation of quinolines. The analogous processes were developed by applying new synthetic tools such as novel catalysts, the microwave irradiation method, etc., whereas recent innovations in new bond forming reactions have allowed for novel strategies to construct the core structures of 2-quinolones beyond the bond disconnections based on two classical reactions. Over the last few decades, some reviews on structure-based, catalyst-based, and bioactivity-based studies have been released. In this focused review, we extensively surveyed recent examples of one-pot reactions, particularly in view of modular approaches. Thus, the contents are categorized as three major sections (two-, three-, and four-component reactions) according to the number of reagents that ultimately compose atoms of the core structures of 2-quinolones. The collected synthetic methods are discussed from the perspectives of strategy, efficiency, selectivity, and reaction mechanism.

Amide Synthesis by Transamidation of Primary Carboxamides

Synthesis ◽  
2020 ◽  
Vol 52 (21) ◽  
pp. 3231-3242
Author(s):  
Sylvain Laclef ◽  
Maria Kolympadi Marković ◽  
Dean Marković
Keyword(s):  
Synthetic Methods ◽  
Amide Bond ◽  
Industrial Chemistry ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Atom Economy ◽  
Bond Forming ◽  
Effective Strategies ◽  
Brönsted Acid ◽  
Metal Catalyzed

The amide functionality is one of the most important and widely used groups in nature and in medicinal and industrial chemistry. Because of its importance and as the actual synthetic methods suffer from major drawbacks, such as the use of a stoichiometric amount of an activating agent, epimerization and low atom economy, the development of new and efficient amide bond forming reactions is needed. A number of greener and more effective strategies have been studied and developed. The transamidation of primary amides is particularly attractive in terms of atom economy and as ammonia is the single byproduct. This review summarizes the advancements in metal-catalyzed and organocatalyzed transamidation methods. Lewis and Brønsted acid transamidation catalysts are reviewed as a separate group. The activation of primary amides by promoter, as well as catalyst- and promoter-free protocols, are also described. The proposed mechanisms and key intermediates of the depicted transamidation reactions are shown.1 Introduction2 Metal-Catalyzed Transamidations3 Organocatalyzed Transamidations4 Lewis and Brønsted Acid Catalysis5 Promoted Transamidation of Primary Amides6 Catalyst- and Promoter-Free Protocols7 Conclusion

Recent Developments in Photochemical and Electrochemical Decarboxylative C(sp3)–N Bond Formation

Synthesis ◽  
2020 ◽  
Vol 52 (09) ◽  
pp. 1357-1368 ◽  
Author(s):  
Lifang Tian ◽  
Yahui Wang ◽  
Yue Zheng ◽  
Xiaoqing Shao ◽  
Velayudham Ramadoss
Keyword(s):  
Rapid Development ◽  
Bond Formation ◽  
Short Review ◽  
Toxic Substances ◽  
Coupling Reactions ◽  
Bond Forming ◽  
Drug Molecules ◽  
Recent Developments ◽  
Metal Catalyzed ◽  
Nitrogen Containing Compounds

Considering the important applications of nitrogen-containing compounds in agrochemical materials and biomolecular drug molecules, research on methods for the construction of C–N bonds quickly and efficiently has become an important topic in synthetic chemistry. Carboxylic acids are inexpensive, stable, and non-toxic substances that are widely present in Nature, which makes them appealing as potential coupling partners for C(sp3)–N bond-forming reactions. Moreover, compared with the well-established transition-metal-catalyzed protocols, the rapid development of photoredox catalysis and electrochemical methods in recent years provides options for chemists to design new synthetic routes. In this short review, we concentrate on the decarboxylative C(sp3)–N coupling reactions mediated by visible light or electricity, with special attention on mechanistic insights.1 Introduction2 Photoredox-Mediated Decarboxylative C(sp3)–N Bond Formation2.1 Intramolecular Decarboxylation2.2 Intermolecular Decarboxylation3 Electrochemistry-Induced Decarboxylative C(sp3)–N Bond Formation3.1 Intramolecular Decarboxylation3.2 Intermolecular Decarboxylation4 Conclusions and Outlook

scholarly journals Intramolecular C(sp3)–H Bond Amination Strategies for the Synthesis of Saturated N-containing Heterocycles

2020 ◽  
Vol 74 (11) ◽  
pp. 895-903
Author(s):  
Jiayu Zhang ◽  
Mónica H. Pérez-Temprano
Keyword(s):  
Transition Metal ◽  
Reductive Elimination ◽  
Efficient Manner ◽  
Bond Forming ◽  
The Past ◽  
Selective Functionalization ◽  
Recent Advances ◽  
Bond Forming Reactions ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

The selective functionalization of C(sp3)–H bonds via intramolecular amination reactions represents a very attractive strategy for the construction of saturated N-containing heterocycles (SNHets). Over the past de- cades, the chemical community has devoted its efforts towards expanding the synthetic toolbox with the aim of facilitating access to these key fragments in a controllable, reproducible and efficient manner. This review covers selected examples of the most recent advances in intramolecular C(sp3)–N bond-forming reactions by three main approaches: (1) the Hofmann-Löffler-Freytag (HLF) reaction; (2) transition-metal-catalyzed nitrene C(sp3)–H inser- tion; and (3) transition-metal-catalyzed ligand-assisted C(sp3)–N bond-forming reactions via a reductive elimination step. We will discuss reactivity, selectivity and the major mechanistic insights into these transformations.

Copper Catalysts in the Synthesis of Five-membered N-polyheterocycles

2018 ◽  
Vol 15 (7) ◽  
pp. 940-971 ◽  
Author(s):  
Navjeet Kaur
Keyword(s):  
Transition Metal ◽  
Organic Synthesis ◽  
Copper Catalysts ◽  
Research Field ◽  
Chemoselective Synthesis ◽  
Specialized Equipment ◽  
Transition Metal Catalyzed ◽  
Synthetic Methodologies ◽  
Metal Catalyzed ◽  
Traditional Approaches

Background: Due to significant biological activity associated with N-, O- and S-heterocycles, a number of reports for their synthesis have appeared in recent decades. Traditional approaches require expensive or highly specialized equipment or would be of limited use to the synthetic organic chemist due to their highly inconvenient approaches. This review summarizes the applications of copper catalysts with the emphasis on their synthetic applications for nitrogen bearing polyheterocylces. In summary, this review article describes the synthesis of a number of five-membered poly heterocyclic rings. Objective: Nowadays new approaches that employ atom-economical and efficient pathway have been developed. The researchers are following natural models to design and synthesize heterocycles. The transition metal catalyzed protocols have attracted the attention as compared to other synthetic methodologies because they use easily available substrates to build multiple substituted complicated molecules directly under mild conditions. In organic synthesis, constituted by transition metal catalyzed coupling transformations are one of the most powerful and useful protocols. The N-heterocycles are synthesized by this convenient and useful tool. Conclusion: The efficient and chemoselective synthesis of heterocycles by this technique has appeared as an important tool. This review shows a highly dynamic research field and the employment of copper catalysts in organic synthesis. Several strategies have been pointed out in the past few years, to meet more sustainable, efficient and environmentally benign chemical products and procedures. The catalytic strategies have been the focus of intense research because they avoid the use of toxic reagents. Among these catalytic strategies, highly rewarding and an important method in heterocycles synthesis is metal catalyzed synthesis.

scholarly journals Modern Synthetic Methods for the Stereoselective Construction of 1,3-Dienes

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 249
Author(s):  
Raquel G. Soengas ◽  
Humberto Rodríguez-Solla
Keyword(s):  
Organic Chemistry ◽  
Natural Products ◽  
Functional Group ◽  
Biological Activities ◽  
Synthetic Methods ◽  
Bond Forming ◽  
Drug Candidates ◽  
The Past ◽  
Wide Range

The 1,3-butadiene motif is widely found in many natural products and drug candidates with relevant biological activities. Moreover, dienes are important targets for synthetic chemists, due to their ability to give access to a wide range of functional group transformations, including a broad range of C-C bond-forming processes. Therefore, the stereoselective preparation of dienes have attracted much attention over the past decades, and the search for new synthetic protocols continues unabated. The aim of this review is to give an overview of the diverse methodologies that have emerged in the last decade, with a focus on the synthetic processes that meet the requirements of efficiency and sustainability of modern organic chemistry.

Nickel-Catalyzed Electronically-Reversed Enantioselective Hydrocarbofunctionalizations of Acrylamides

Synlett ◽  
2021 ◽  
Author(s):  
Lou Shi ◽  
Wei Shu
Keyword(s):  
Nickel Catalyst ◽  
Functional Group ◽  
Optically Active ◽  
Forming Process ◽  
Carbon Bond ◽  
Bond Forming ◽  
Synthetic Strategy ◽  
Carbon Carbon Bond ◽  
Wide Range ◽  
Simple Protocol

Asymmetric hydrocarbofunctionalizations of alkenes has emerged as an efficient synthetic strategy for accessing optically active molecules via carbon-carbon bond-forming process from readily available alkenes and carbo-electrophiles. Herein, we present a summary of the efforts from our group to control the regio- and enantioselectivity of hydrocarbofunctionalizations of electron-deficient alkenes with a nickel catalyst and chiral bisoxazolidine ligand. The reaction undergoes electron-reversed hydrocarbofunctionalizations acrylamides with excellent enantioselectivity. This operationally simple protocol enables the asymmetric hydroalkylation, hydrobenzylation and hydropropargylation of acrylamides. This reaction is useful for preparing a wide range of α-branched chiral amides with broad functional group tolerance.

scholarly journals Towards a Paradigm Shift in Polar Organometallic Chemistry

2020 ◽  
Vol 74 (9) ◽  
pp. 681-688 ◽  
Author(s):  
Eva Hevia
Keyword(s):  
Organometallic Chemistry ◽  
Synergistic Effects ◽  
Chemical Properties ◽  
Deep Eutectic Solvents ◽  
Chemical Transformations ◽  
Organometallic Reagents ◽  
Cooperative Effects ◽  
Bond Forming ◽  
Synthetic Methodologies ◽  
Metal Reagents

Core tools of synthetic chemistry, polar organometallic reagents (typified by organolithium and Grignard reagents) are used worldwide for constructing compounds, especially aromatic compounds, which are ubiquitous in organic chemistry and thus in numerous commodities essential to everyday life. By isolation and characterisation of key organometallic intermediates, research in our group has led to the design of polar mixed-metal reagents imbued with synergistic effects that display chemical properties and reactivity profiles far exceeding the limits of traditional single-metal reagents. These studies have improved existing, or established new fundamentally important, synthetic methodologies based on either stoichiometric or catalytic reactions. Bimetallic cooperative effects have been demonstrated in an impressive array of important bond forming reactions including deprotonative metallation, transition metal-free C–C bond formation and metal–halogen exchange to name just a few. Towards greener, more sustainable, safer chemical transformations, our group has also pioneered the use of polar organometallic reagents under air and/or with water present using biorenewable solvents such as Deep Eutectic Solvents (DES) and 2-methyl THF. Herein we summarize some of our recent efforts in this intriguing area, which we believe can make inroads towards a step change in the practice and future scope of polar organometallic chemistry.

scholarly journals Palladium-Catalysed Synthesis and Transformation of Quinolones

Molecules ◽  
2019 ◽  
Vol 24 (2) ◽  
pp. 228 ◽  
Author(s):  
Vera L. M. Silva ◽  
Artur M. S. Silva
Keyword(s):  
Multiple Bond ◽  
Single Step ◽  
Molecular Structures ◽  
Synthetic Methods ◽  
Complex Molecules ◽  
Bond Forming ◽  
Drug Candidates ◽  
Rapid Construction ◽  
Wide Range ◽  
Privileged Structures

Palladium-catalysed reactions have had a large impact on synthetic organic chemistry and have found many applications in target-oriented synthesis. Their widespread use in organic synthesis is due to the mild conditions associated with the reactions together with their tolerance of a wide range of functional groups. Moreover, these types of reactions allow the rapid construction of complex molecules through multiple bond-forming reactions in a single step, the so-called tandem processes. Pd-catalysed reactions have been applied to the synthesis of a large number of natural products and bioactive compounds, some of them of complex molecular structures. This review article aims to present an overview of the most important Pd-catalysed reactions employed in the synthesis and transformations of quinolin-2(1H)-ones and quinolin-4(1H)-ones. These compounds are widely recognized by their diverse bioactivity, being privileged structures in medicinal chemistry and useful structural moieties for the development of new drug candidates. Furthermore, they hold significant interest due to their host–guest chemistry; applications in chemical, biochemical and environmental analyses and use in the development of new synthetic methods. In some cases, the quinolone formation step cannot be ascribed to a claimed Pd-catalysed reaction but this reaction is crucial to get the appropriate substrate for cyclization into the quinolone. Herein we present and discuss different economical, efficient and selective synthetic strategies to access quinolone-type compounds.

Sign in / Sign up

Export Citation Format

Share Document