4.20 Addition of Ketocarbenes to Alkenes, Alkynes, and Aromatic Systems

Garcı́a, José I.; Salvatella, Luis; Pires, Elísabet; Fraile, José M.; Mayoral, J. A.

doi:10.1016/b978-0-08-097742-3.00426-2

Cited by 3 publications

(3 citation statements)

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“…Thus, research has focused in the development of efficient highly diastereo-and enantioselective methods for the synthesis of cyclopropanes [3][4][5]. Among them, a common and versatile procedure is the metal-catalyzed decomposition of diazo compounds in the presence of olefins, for which various efficient catalysts have been developed [6].…”

Section: Introductionmentioning

confidence: 99%

“…Copper-based catalysts are particularly attractive due to their high efficiency in asymmetric cyclopropanation reactions [7] and their relatively low cost in comparison with other metal catalysts. In order to gain better understanding of the stereoselectivity governing factors, and thereby upgrade the ability to design more efficient catalytic systems, the mechanism of the copper-catalyzed cyclopropanation reaction of olefins with diazo compounds has been experimentally [6] and theoretically [8] studied in recent years, and the pathway for the global catalytic cycle is now well established. Thus, it is agreed that the active catalyst is a Cu(I) species, irrespective of the oxidation state of the copper complex used as the precatalyst, since Cu(II) complexes are reduced to Cu(I) derivatives by diazo compounds under the reaction conditions [9].…”

Section: Introductionmentioning

confidence: 99%

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Copper-catalyzed cyclopropanation reaction of but-2-ene

et al. 2018

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The mechanism of the copper(I)-catalyzed cyclopropanation reaction for methyl diazoacetate with both (Z)- and (E)-but-2-ene stereoisomers has been studied using the 6-311++G(d,p) basis set by means of M06-2X and O3LYP functionals. According to both methods, the rate-limiting step is the formation of a copper-carbene intermediate, formed by association between methyl diazoacetate and bis(acetonitrile)-copper(I) ion with the concomitant extrusion of dinitrogen. Cis/trans diastereoselectivity for the cyclopropanation reaction of a 1,2-disubstituted alkene ((Z)-but-2-ene) has been theoretically studied for the first time through the proper location of transition states on the potential-energy surface with the O3LYP method, since no transition structures could be found with the M06-2X functional due to the extreme flatness of the potential-energy surface. The calculated stereoselectivities involving two acetonitrile ligands or one dichloromethane molecule show qualitative agreement with experimental data. This study allows attributing the origin of the selectivity to steric interactions between the ligands of the catalyst system and the olefin substituents. The comparison between the corresponding activation barriers for the direct insertion step shows a higher reactivity for the Z stereoisomer of but-2-ene, consistently with the larger reactant destabilization through steric interactions.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Copper-catalyzed cyclopropanation reaction of but-2-ene

et al. 2018

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“…Cyclopropanation of methyl fatty esters with EDA catalysed by Rh 2 (OAc) 4 Rhodium is the most commonly used catalyst for cyclopropanation reactions, 29,30 and hence Rh 2 (OAc) 4 was tested as catalyst in the three reactions described above. The results are summarized in Table 3.…”

Section: 28mentioning

confidence: 99%

Challenging cyclopropanation reactions on non-activated double bonds of fatty esters

et al. 2017

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Monounsaturated fatty esters with non-activated double bonds have been made to react with two different diazocompounds, ethyl diazoacetate (EDA) and dimethyl diazomalonate (DDM), in copper and rhodium catalyzed cyclopropanation reactions. The corresponding cyclopropanes have been obtained with quantitative or nearly quantitative yields (>99%) in all the cases, with only the exception of the reaction of methyl elaidate, an E alkene, with the less reactive DDM. For the first time, the two stereoisomers of ethyl (2R*,3S*)-2-(7-methoxycarbonyl)heptyl-3-octylcyclopropane-1-carboxylate, obtained from the reaction of methyl oleate and EDA, have been separated and fully characterized. Finally, the diesters and triesters with cyclopropane structure have been reduced to diols and triols, and hydrolyzed to the corresponding diacids and triacids, to demonstrate the potential usefulness of this methodology to prepare monomers from renewable sources.

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Amino‐Ene Click Reaction of Electron‐Deficient π‐Conjugated Molecules with Negative Activation Enthalpies

Sanematsu

Nagata

Takeuchi

et al. 2023

Chemistry A European J

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An amino-ene click reaction is a type of aza-Michael addition reaction that is congruent with click chemistry in terms of its reaction efficiency and rate under mild conditions. The amino-ene click reaction is increasingly recognized as a prominent synthetic tool to form CÀ N bonds in the context of organic materials chemistry and polymer chemistry. Herein, an unconventional amino-ene click reaction with negative activation enthalpies, in which an electron-deficient π-conjugated molecule, such as a naphthalenediimide, reacts with an amine faster at lower temperatures is reported. The detailed study of the reaction mechanism reveals that the amino-ene click reaction proceeds via a pre-equilibrium reaction, the key to which is the formation of a stable reaction intermediate due to the solvation and charge delocalization on the π-core. By optimizing the reaction conditions, it was demonstrated that the amino-ene click reaction proceeded faster at 273 K than at 347 K, which was easily observed visually.

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4.20 Addition of Ketocarbenes to Alkenes, Alkynes, and Aromatic Systems

Cited by 3 publications

References 918 publications

Copper-catalyzed cyclopropanation reaction of but-2-ene

Copper-catalyzed cyclopropanation reaction of but-2-ene

Challenging cyclopropanation reactions on non-activated double bonds of fatty esters

Amino‐Ene Click Reaction of Electron‐Deficient π‐Conjugated Molecules with Negative Activation Enthalpies

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