Asymmetric Epoxidation of Alkylidenemalononitriles: Key Step for One-Pot Approach to Enantioenriched 3-Substituted Piperazin-2-ones

Meninno, Sara; Vidal‐Albalat, Andreu; Lattanzi, Alessandra

doi:10.1021/acs.orglett.5b02186

Cited by 47 publications

(23 citation statements)

References 52 publications

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“…Finally, in 2013, Nair and co‐workers utilized quinine ( 36 ), which activates the oxidant and the substrate via a stable intermediate (Figure ) . Lattanzi and co‐workers were able to match the cinchona alkaloid backbone with thioureas 37 and 38 by utilizing compounds with cyano groups in the substrate for hydrogen‐bonding recognition (Figure ) …”

Section: H2o2: a Very Useful Oxidantmentioning

confidence: 99%

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Green Organocatalytic Oxidative Methods using Activated Ketones

2018

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Alkenes are very important moieties in organic chemistry and have been employed as starting materials for the synthesis of important organic compounds. In this review, we present organocatalytic reactions in which alkenes play a central role, especially their organocatalytic oxidation to epoxides. This topic plays a pivotal role in our recent research, for which we utilize H2O2 as a green oxidant and a ketone as the catalyst. Extension to other oxidative transformations is also presented.

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Section: H2o2: a Very Useful Oxidantmentioning

confidence: 99%

“…www.chemcatchem.org 38 by utilizingc ompounds with cyano groups in the substrate for hydrogen-bonding recognition (Figure 9). [85,86] Cyano groups stabilize the intermediate by developing hydrogen bonds with the catalyst (Figure 10).…”

Section: Scheme20mentioning

confidence: 99%

Green Organocatalytic Oxidative Methods using Activated Ketones

2018

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“…In this manner,p eroxide anions can be integrated in our previously established reactivity scales,which makes it possible to directly compare their reactivities with those of other types of nucleophiles. [14] NMR analysis of the crude products of the reactions of 9a and 9b with 5c showed formation of the epoxides 11 a,b in > 80 %y ield. [14] NMR analysis of the crude products of the reactions of 9a and 9b with 5c showed formation of the epoxides 11 a,b in > 80 %y ield.…”

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Solvation Accounts for the Counterintuitive Nucleophilicity Ordering of Peroxide Anions

et al. 2017

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The nucleophilic reactivities (N, s ) of peroxide anions (generated from aromatic and aliphatic peroxy acids or alkyl hydroperoxides) were investigated by following the kinetics of their reactions with a series of benzhydrylium ions (Ar CH ) in alkaline aqueous solutions at 20 °C. The second-order rate constants revealed that deprotonated peroxy acids (RCO ), although they are the considerably weaker Brønsted bases, react much faster than anions of aliphatic hydroperoxides (ROO ). Substitution of the rate constants of their reactions with benzhydrylium ions into the linear free energy relationship lg k=s (N+E) furnished nucleophilicity parameters (N, s ) of peroxide anions, which were successfully applied to predict the rates of Weitz-Scheffer epoxidations. DFT calculations with inclusion of solvent effects by means of the Integral Equation Formalism version of the Polarizable Continuum Model were performed to rationalize the observed reactivities.

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“…Ordnung k 2 (Tabelle 1) fürd en Angriff der Peroxid-Anionen 1-5 an den Benzhydrylium-Ionen 6b-e [12] aus den Steigungen der linearen Korrelationen von k 1 (= k obs Àk OH [HO À ]) mit den Konzen-trationen der Peroxid-Anionen bestimmen (Abbildung 2C). [14] Die NMR-Analyse der Rohprodukte der Reaktionen von 9a und 9b mit 5c ergab, dass die Epoxide 11 a,b in über 80 %A usbeute gebildet wurden. Dies weist auf analoge Reaktionsmechanismen und die Anwendbarkeit von Gleichung (1) hin.…”

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Solvatation als Ursache für die unerwartete Nucleophilie‐Reihung von Peroxid‐Anionen

et al. 2017

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Die nucleophilen Reaktivitäten (N,s N )von Peroxid-Anionen (aus aromatischen und aliphatischen Persäuren oder Alkylhydroperoxiden generiert) wurden durch Messung der Kinetik ihrer Reaktionen mit Benzhydrylium-Ionen (Ar 2 CH + ) in alkalischer wässriger Lçsung bei 20 8 8Cb estimmt. Überraschenderweise reagieren die Peroxycarboxylate RCO 3 À trotz ihrer deutlich geringeren Brønsted-Basizitätv iel schneller als die Alkylperoxid-Anionen ROO À .E insetzen der Geschwindigkeitskonstanten ihrer Reaktionen mit Benzhydrylium-Ionen in die lineare Freie-Energie-Beziehung lg k = s N (N + E) lieferte die Nucleophilie-Parameter (N,s N )d er Peroxid-Anionen, die es ermçglichten, Geschwindigkeiten von Weitz-Scheffer-Epoxidierungen vorherzusagen. Um die beobachtete Reaktivitätsreihung zu erklären, wurden DFT-Rechnungen durchgeführt, wobei Lçsungsmitteleffekte durchdie "Integral-Equation-Formalism"-Version des "Polarizable Continuum Model" berücksichtigt wurden.Abbildung 1. Untersuchte Peroxid-Anionen 1-5 und als Referenzelektrophilev erwendete Benzhydrylium-Ionen (Gegenion: BF 4 À ; Elektrophilie E aus Lit. [9]).

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Asymmetric Epoxidation of Alkylidenemalononitriles: Key Step for One-Pot Approach to Enantioenriched 3-Substituted Piperazin-2-ones

Cited by 47 publications

References 52 publications

Green Organocatalytic Oxidative Methods using Activated Ketones

Green Organocatalytic Oxidative Methods using Activated Ketones

Solvation Accounts for the Counterintuitive Nucleophilicity Ordering of Peroxide Anions

Solvatation als Ursache für die unerwartete Nucleophilie‐Reihung von Peroxid‐Anionen

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