scholarly journals Metal-catalyzed organic reactions by Resonant Acoustic Mixing

Author(s):  
Lori Gonnet ◽  
Cameron Lennox ◽  
Jean-Louis Do ◽  
Ivani Malvestiti ◽  
Stefan Koenig ◽  
...  

We introduce catalytic organic synthesis by Resonant Acoustic Mixing (RAM): a mechanochemical methodology that does not require bulk solvent or milling media. Using as model reactions ruthenium-catalyzed ring-closing metathesis, ene-yne metathesis and copper-catalyzed sulfonamide-isocyanate coupling, we demonstrate RAM-based mechanochemical synthesis that is faster and operationally simpler than conventional ball milling. Moreover, the method can be readily scaled-up, as demonstrated by straightforward catalytic synthesis of the antidiabetic drug Tolbutamide from hundreds of milligrams to at least 10 grams, without any significant changes in reaction conditions.

2020 ◽  
Vol 07 ◽  
Author(s):  
Rajib Sarkar ◽  
Chhanda Mukhopadhyay

Abstract:: The use of small organic molecules as organocatalysts in organic synthesis has intensely studied over the past decade. In this emerging field, considerable study has led to the introduction of various efficient organocatalyzed synthetic methods of carbon-carbon and carbon-hetero atom bond formations. The use of these organocatalysts also emerged environmentally benign reaction conditions compared to the metal catalyzed transformations. In this review, we make a special attention on the most recent organocatalytic protocols reported for the synthesis of heterocycles. The works have been outlined by depending on the organocatalysts used as (i) nitrogen based molecules as organocatalyst, (ii) NHCs as organocatalyst, and (iii) phosphorus based molecules as organocatalyst. The discussion intends to reveal the scope as well as vitality of organocatalysis in the area of heterocycle synthesis.


Synlett ◽  
2020 ◽  
Author(s):  
Zheng-Hua Zhang ◽  
He Wei ◽  
Zhong-Liang Li ◽  
Xin-Yuan Liu

AbstractThe direct C(sp3)–H functionalization is one of the major research topics in synthetic chemistry since C(sp3)–H bonds are ubiquitous in every aspect of chemistry. Despite impressive advances in transition-metal-catalyzed C(sp3)–H activation, the radical-initiated process via hydrogen atom abstraction (HAA) of C(sp3)–H bonds represents a more appealing strategy owing to the mild reaction conditions and good regioselectivity. Given the importance of alkynes as versatile synthons in organic synthesis and key structural motifs in drug discovery, great efforts have been made toward their synthesis via the combination of HAA and alkynylation process in recent years. This review summarizes the recent progress in radical-initiated C(sp3)–H alkynylation reactions with emphasis on the alkynylating reagents and mechanistic discussion.1 Introduction2 Alkynylation of C(sp3)–H via Intermolecular Hydrogen Atom Abstraction3 Alkynylation of C(sp3)–H via Intramolecular Hydrogen Atom Abstraction4 Conclusion


Author(s):  
Alex L. Bagdasarian ◽  
Stasik Popov ◽  
Benjamin Wigman ◽  
Wenjing Wei ◽  
woojin lee ◽  
...  

Herein we report the 3,5bistrifluoromethylphenyl urea-catalyzed functionalization of unactivated C–H bonds. In this system, the urea catalyst mediates the formation of high-energy vinyl carbocations that undergo facile C–H insertion and Friedel–Crafts reactions. We introduce a new paradigm for these privileged scaffolds where the combination of hydrogen bonding motifs and strong bases affords highly active Lewis acid catalysts capable of ionizing strong C–O bonds. Despite the highly Lewis acidic nature of these catalysts that enables triflate abstraction from sp<sup>2</sup> carbons, these newly found reaction conditions allow for the formation of heterocycles and tolerate highly Lewis basic heteroaromatic substrates. This strategy showcases the potential utility of dicoordinated vinyl carbocations in organic synthesis.<br>


2020 ◽  
Author(s):  
Alex L. Bagdasarian ◽  
Stasik Popov ◽  
Benjamin Wigman ◽  
Wenjing Wei ◽  
woojin lee ◽  
...  

Herein we report the 3,5bistrifluoromethylphenyl urea-catalyzed functionalization of unactivated C–H bonds. In this system, the urea catalyst mediates the formation of high-energy vinyl carbocations that undergo facile C–H insertion and Friedel–Crafts reactions. We introduce a new paradigm for these privileged scaffolds where the combination of hydrogen bonding motifs and strong bases affords highly active Lewis acid catalysts capable of ionizing strong C–O bonds. Despite the highly Lewis acidic nature of these catalysts that enables triflate abstraction from sp<sup>2</sup> carbons, these newly found reaction conditions allow for the formation of heterocycles and tolerate highly Lewis basic heteroaromatic substrates. This strategy showcases the potential utility of dicoordinated vinyl carbocations in organic synthesis.<br>


2018 ◽  
Vol 15 (7) ◽  
pp. 940-971 ◽  
Author(s):  
Navjeet Kaur

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.


Author(s):  
Jie Jack Li ◽  
Chris Limberakis ◽  
Derek A. Pflum

Searching for reaction in organic synthesis has been made much easier in the current age of computer databases. However, the dilemma now is which procedure one selects among the ocean of choices. Especially for novices in the laboratory, it becomes a daunting task to decide what reaction conditions to experiment with first in order to have the best chance of success. This collection intends to serve as an "older and wiser lab-mate" one could have by compiling many of the most commonly used experimental procedures in organic synthesis. With chapters that cover such topics as functional group manipulations, oxidation, reduction, and carbon-carbon bond formation, Modern Organic Synthesis in the Laboratory will be useful for both graduate students and professors in organic chemistry and medicinal chemists in the pharmaceutical and agrochemical industries.


2019 ◽  
Vol 15 ◽  
pp. 963-970 ◽  
Author(s):  
Sora Park ◽  
Jeung Gon Kim

Mechanochemical polymerization is a rapidly growing area and a number of polymeric materials can now be obtained through green mechanochemical synthesis. In addition to the general merits of mechanochemistry, such as being solvent-free and resulting in high conversions, we herein explore rate acceleration under ball-milling conditions while the conventional solution-state synthesis suffer from low reactivity. The solvent-free mechanochemical polymerization of trimethylene carbonate using the organocatalysts 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) are examined herein. The polymerizations under ball-milling conditions exhibited significant rate enhancements compared to polymerizations in solution. A number of milling parameters were evaluated for the ball-milling polymerization. Temperature increases due to ball collisions and exothermic energy output did not affect the polymerization rate significantly and the initial mixing speed was important for chain-length control. Liquid-assisted grinding was applied for the synthesis of high molecular weight polymers, but it failed to protect the polymer chain from mechanical degradation.


2020 ◽  
Vol 5 (5) ◽  
Author(s):  
Laura Raimondi ◽  
Chiara Faverio ◽  
Monica Fiorenza Boselli

AbstractChiral molecules hold a mail position in Organic and Biological Chemistry, so pharmaceutical industry needs suitable strategies for drug synthesis. Moreover, Green Chemistry procedures are increasingly required in order to avoid environment deterioration. Catalytic synthesis, in particular organocatalysis, in thus a continuously expanding field. A survey of more recent researches involving chiral imidazolidinones is here presented, with a particular focus on immobilized catalytic systems.


Synlett ◽  
2020 ◽  
Author(s):  
Margaret R Jones ◽  
Nathan D. Schley

The field of catalytic C-H borylation has grown considerably since its founding, providing a means for the preparation of synthetically versatile organoborane products. While sp2 C-H borylation methods have found widespread and practical use in organic synthesis, the analogous sp3 C-H borylation reaction remains challenging and has seen limited application. Existing catalysts are often hindered by incomplete consumption of the diboron reagent, poor functional group tolerance, harsh reaction conditions, and the need for excess or neat substrate. These challenges acutely affect C-H borylation chemistry of unactivated hydrocarbon substrates, which has lagged in comparison to methods for the C-H borylation of activated compounds. Herein we discuss recent advances in sp3 C-H borylation of undirected substrates in the context of two particular challenges: (1) utilization of the diboron reagent and (2) the need for excess or neat substrate. Our recent work on the application of dipyridylarylmethane ligands in sp3 C-H borylation has allowed us to make contributions in this space and has presented an additional ligand scaffold to supplement traditional phenanthroline ligands.


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