scholarly journals Stable CAAC-based Ruthenium Complexes for Dynamic Olefin Metathesis Under Mild Conditions

2021 ◽  
Author(s):  
Oleksandr Kravchenko ◽  
Brian J.J. Timmer ◽  
Maurice Biedermann ◽  
Andrew Kentaro Inge ◽  
Olof Ramstrom
Keyword(s):  
Olefin Metathesis ◽  
High Stability ◽  
Room Temperature ◽  
Functional Group ◽  
Biologically Active ◽  
Dynamic Covalent Chemistry ◽  
Mild Conditions ◽  
Cross Metathesis ◽  
Potential Applications ◽  
Metathesis Catalysts

<p>A series of olefin metathesis catalysts bearing cyclic (alkyl)(amino)carbene (CAAC) ligands of varying size and steric demand has been synthesized and evaluated in ring-closing-, self-, and cross-metathesis reactions at room temperature. The catalysts were also probed for potential applications in dynamic covalent chemistry. The majority of the catalysts showed high stability, and remained active in the reaction mixtures for several days, including in methanol-based solutions. Higher temperatures could be used to control the reactivity towards sterically challenging substrates, enabling formation of tetrasubstituted olefins. The CAAC complexes exhibited remarkable functional group tolerance towards heteroaromatic and nucleophilic additives, making them potentially useful in the screening of biologically active compounds.</p>

scholarly journals Stable CAAC-based Ruthenium Complexes for Dynamic Olefin Metathesis Under Mild Conditions

2021 ◽  
Author(s):  
Oleksandr Kravchenko ◽  
Brian J.J. Timmer ◽  
Maurice Biedermann ◽  
Andrew Kentaro Inge ◽  
Olof Ramstrom
Keyword(s):  
Olefin Metathesis ◽  
High Stability ◽  
Room Temperature ◽  
Functional Group ◽  
Biologically Active ◽  
Dynamic Covalent Chemistry ◽  
Mild Conditions ◽  
Cross Metathesis ◽  
Potential Applications ◽  
Metathesis Catalysts

<p>A series of olefin metathesis catalysts bearing cyclic (alkyl)(amino)carbene (CAAC) ligands of varying size and steric demand has been synthesized and evaluated in ring-closing-, self-, and cross-metathesis reactions at room temperature. The catalysts were also probed for potential applications in dynamic covalent chemistry. The majority of the catalysts showed high stability, and remained active in the reaction mixtures for several days, including in methanol-based solutions. Higher temperatures could be used to control the reactivity towards sterically challenging substrates, enabling formation of tetrasubstituted olefins. The CAAC complexes exhibited remarkable functional group tolerance towards heteroaromatic and nucleophilic additives, making them potentially useful in the screening of biologically active compounds.</p>

Cross-Metathesis/Intramolecular (Hetero-)Michael Addition: A Convenient Sequence for the Generation of Carbo- and Heterocycles

Synthesis ◽  
2017 ◽  
Vol 49 (13) ◽  
pp. 2787-2802 ◽  
Author(s):  
María Sánchez-Roselló ◽  
Carlos del Pozo ◽  
Javier Miró
Keyword(s):  
Michael Addition ◽  
Olefin Metathesis ◽  
High Stability ◽  
Functional Group ◽  
Domino Reactions ◽  
Simple Manner ◽  
Great Ability ◽  
Carbene Complexes ◽  
Cross Metathesis ◽  
Metathesis Reactions

The high stability and functional group compatibility of ruthenium carbene complexes confer them a great ability to catalyze domino processes. For this reason, the combination of metathesis reactions with additional transformations in a domino fashion has been exploited extensively, with the result of expanding the utility of ruthenium carbene complexes beyond that of just olefin metathesis. Among those domino processes, it is worth mentioning the sequence of cross-metathesis/intramolecular Michael addition, which allows for the generation of a wide variety of carbo- and heterocycles in a very simple manner, taking advantage of the benefits of domino reactions. Carbon-, oxygen- and nitrogen-centered nucleophiles are good partners in this protocol, the versatility of which has been illustrated with the synthesis of several biologically important compounds.1 Introduction2 Cross Metathesis/Intramolecular Aza-Michael Addition Sequences3 Cross Metathesis/Intramolecular Oxa-Michael Addition Sequences4 Cross Metathesis/Intramolecular Michael Addition Sequences5 Conclusions and Outlook

scholarly journals Olefin metathesis in air

2015 ◽  
Vol 11 ◽  
pp. 2038-2056 ◽  
Author(s):  
Lorenzo Piola ◽  
Fady Nahra ◽  
Steven P Nolan
Keyword(s):  
Transition Metal ◽  
Olefin Metathesis ◽  
Functional Group ◽  
High Oxidation State ◽  
Catalytic Systems ◽  
Metal Centers ◽  
Early Transition Metal ◽  
Significant Interest ◽  
High Oxidation ◽  
Metathesis Catalysts

Since the discovery and now widespread use of olefin metathesis, the evolution of metathesis catalysts towards air stability has become an area of significant interest. In this fascinating area of study, beginning with early systems making use of high oxidation state early transition metal centers that required strict exclusion of water and air, advances have been made to render catalysts more stable and yet more functional group tolerant. This review summarizes the major developments concerning catalytic systems directed towards water and air tolerance.

scholarly journals Difunctionalization of alkenes with iodine and tert-butyl hydroperoxide (TBHP) at room temperature for the synthesis of 1-(tert-butylperoxy)-2-iodoethanes

2017 ◽  
Vol 13 ◽  
pp. 2023-2027 ◽  
Author(s):  
Hao Wang ◽  
Cui Chen ◽  
Weibing Liu ◽  
Zhibo Zhu
Keyword(s):  
Room Temperature ◽  
Synthetic Methods ◽  
Chemical Modifications ◽  
One Pot ◽  
Butyl Hydroperoxide ◽  
Radical Intermediates ◽  
Mild Conditions ◽  
Tert Butyl Hydroperoxide ◽  
Potential Applications

We developed a direct vicinal difunctionalization of alkenes with iodine and TBHP at room temperature. This iodination and peroxidation in a one-pot synthesis produces 1-(tert-butylperoxy)-2-iodoethanes, which are inaccessible through conventional synthetic methods. This method generates multiple radical intermediates in situ and has excellent regioselectivity, a broad substrate scope and mild conditions. The iodine and peroxide groups of 1-(tert-butylperoxy)-2-iodoethanes have several potential applications and allow further chemical modifications, enabling the preparation of synthetically valuable molecules.

Synthesis of O-Aroyl-N,N-dimethylhydroxylamines through Hypervalent Iodine-Mediated Amination of Carboxylic Acids with N,N-Dimethylformamide

Synthesis ◽  
2017 ◽  
Vol 49 (18) ◽  
pp. 4303-4308 ◽  
Author(s):  
Dong Li ◽  
Chuancheng Zhang ◽  
Qiang Yue ◽  
Zhen Xiao ◽  
Xianglan Wang ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Room Temperature ◽  
Functional Group ◽  
Hypervalent Iodine ◽  
Electrophilic Amination ◽  
Mild Conditions

An efficient protocol for the synthesis of O-aroyl-N,N-dimethylhydroxylamines, which are important electrophilic amination reagents, is described. The reaction between carboxylic acids and N,N-dimethylformamide is mediated by hypervalent iodine and occurs under mild conditions at room temperature to give the desired products in good yields. The process shows good functional group compatibility and air and moisture tolerance.

A facile new procedure for the deprotection of allyl ethers under mild conditions

2000 ◽  
Vol 78 (6) ◽  
pp. 838-845 ◽  
Author(s):  
Yun-Jin Hu ◽  
Romyr Dominique ◽  
Sanjoy Kumar Das ◽  
René Roy
Keyword(s):  
Key Words ◽  
Catalytic System ◽  
Olefin Metathesis ◽  
Allyl Ether ◽  
Metathesis Reaction ◽  
Grubbs Catalyst ◽  
Allyl Ethers ◽  
Mild Conditions ◽  
Cross Metathesis ◽  
Allylic Ethers

A novel isomerization of O-allyl glycosides into prop-1-enyl glycosides was observed instead of cross-metathesis during an olefin metathesis reaction using Grubbs' ruthenium benzylidene catalyst (Cy3P)2RuCl2=CHPh (1), N-allyltritylamine, and N,N-diisopropylethylamine as necessary auxiliary reagents. In the search for a better catalytic system, it has been found that dichlorotris(triphenylphosphine)ruthenium(II), [(C6H5)3P]3RuCl2, (2) was much more efficient for the isomerization of allylic ethers. The labile prop-1-enyl group was easily hydrolyzed using HgCl2-HgO and the hemiacetals (25-32) were isolated in excellent yields (ca. 90%).Key words: allyl ether, carbohydrate, Grubbs' catalyst, isomerization, metathesis, deprotection.

scholarly journals A Versatile New Reagent for Nitrosation under Mild Conditions

2021 ◽  
Author(s):  
Jordan D. Galloway ◽  
Cristian Sarabia ◽  
James C. Fettinger ◽  
Hrant Hratchian ◽  
Ryan Baxter
Keyword(s):  
Room Temperature ◽  
Computational Analysis ◽  
Functional Group ◽  
Nitroso Compounds ◽  
Chemical Reagent ◽  
Experimental Conditions ◽  
X Ray ◽  
Mild Conditions ◽  
Rotational Isomers ◽  
First Time

We report a new chemical reagent for transnitrosation under mild experimental conditions. This new reagent is stable to air and moisture across a broad range of temperatures, and is effective for transnitrosation in multiple solvents. Compared to traditional nitrosation methods, our reagent shows high functional group tolerance for substrates that are susceptible to oxidation or reversible transnitrosation. Several challenging nitroso-compounds are accessed here for the first time, including 15N isotopologues. X-ray data confirms two rotational isomers of the reagent are configurationally stable at room temperature, although only one isomer is effective for transnitrosation. Computational analysis describes the energetics of rotamer interconversion, including interesting geometry-dependent hybridization ef-fects.

Additive- and Oxidant-Free Expedient Synthesis of Benzimidazoles Catalyzed by Cobalt Nanocomposites on N-Doped Carbon

Synlett ◽  
2019 ◽  
Vol 30 (03) ◽  
pp. 319-324 ◽  
Author(s):  
Zhaozhan Wang ◽  
Tao Song ◽  
Yong Yang
Keyword(s):  
Functional Group ◽  
Direct Synthesis ◽  
Biologically Active ◽  
One Pot ◽  
Mild Conditions ◽  
Wide Range ◽  
High Yields

A one-pot direct synthesis of a wide range of biologically active benzimidazoles through coupling of phenylenediamines and aldehydes catalyzed by a highly recyclable nonnoble cobalt nanocomposite was developed. A broad set of benzimidazoles can be efficiently synthesized in high yields and with good functional-group tolerance under additive- and oxidant-free mild conditions. The catalyst can be easily recycled for successive uses, and the process permits gram-scale syntheses of benzimidazoles.

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