The Use of Silver Oxide in the Preparation of Diaryldiazomethanes

Schroeder, William; Katz, L.

doi:10.1021/jo01370a003

Cited by 49 publications

(21 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…After a simple work‐up, these hydrazones were directly used in the oxidation step toward diazoalkanes formation. While many oxidizing reagents have been tested, the combined basicity and oxidative ability of silver oxide (Ag 2 O) already proved to be sufficiently reactive to generate unstable diazoalkanes . However, low yields were obtained because of degradation of the freshly formed diazo on Ag I and reduced Ag 0 , as well as during the long and tedious purification processes.…”

Section: Figurementioning

confidence: 99%

Safe and Facile Access to Nonstabilized Diazoalkanes Using Continuous Flow Technology

et al. 2018

View full text Add to dashboard Cite

Despite the high synthetic potential of nonstabilized diazo compounds, their utilization has always been hampered by stability, toxicity, and safety issues. The present method opens up access to the most reactive nonstabilized diazoalkanes. Among diazo compounds, nonstabilized alkyl diazo compounds are the least represented because of their propensity to degrade during preparation. The continuous flow oxidation process of hydrazones on a silver oxide column afforded an output stream of base- and metal-free pure diazo solution in dichloromethane. Starting from innocuous ketones and aldehydes, this methodology allows the production of a broad range of unprecedented diazoalkanes compounds in excellent yields, while highlighting their synthetic potential and the possibility of safe large-scale diazo production.

show abstract

Section: Figurementioning

confidence: 99%

Safe and Facile Access to Nonstabilized Diazoalkanes Using Continuous Flow Technology

et al. 2018

View full text Add to dashboard Cite

show abstract

“…While many oxidizing reagents have been tested, [16] the combined basicity and oxidative ability of silver oxide (Ag 2 O) already proved to be sufficiently reactive to generate unstable diazoalkanes. [12,17] However,l ow yields were obtained because of degradation of the freshly formed diazo on Ag I and reduced Ag 0 ,aswell as during the long and tedious purification processes.I twas anticipated that ac ontinuous process using ac olumn packed with Ag 2 Oa tc ontrolled low temperature would overcome degradation of the formed diazo by minimizing contact between the diazo and Ag 2 O/ Ag 0 ,w hich strongly catalyzed its decomposition. [12] Initial investigations focused on dimethyl hydrazone (1a) as am odel substrate for the generation of 2-diazopropane (2a).…”

mentioning

confidence: 99%

Safe and Facile Access to Nonstabilized Diazoalkanes Using Continuous Flow Technology

et al. 2018

View full text Add to dashboard Cite

Die Hintergrundinformationen zu dieser Zuschrift enthalten eine inkorrekte Struktur für Verbindung 3k,erhalten nach [3þ2]-Cycloaddition von 2k mit Acetylendicarbonsäuredimethylester.Ursprünglich wurde das Pyrazolenin abgebildet, in diesem Beispiel wurde allerdings das Pyrazol 3k erhalten. Diese Struktur ist in den revidierten Hintergrundinformationen korrigiert, die online mit dieser Berichtigung verçffentlicht werden. Darüber hinaus enthält die Reaktionsgleichung in Tabelle 1einen Fehler,der in der hier abgebildeten Fassung korrigiert ist.Schwerer wiegt aber,dass die Verbindungen 5a bis 5d inkorrekt als Cyclopropane beschrieben wurden. Während die Autoren zunächst davon ausgingen, dass die 1-Pyrazoline aus den [3þ2]-Cycloadditionen mit Alkenen sich spontan in die gewünschten Cyclopropane umwandeln (Gasentwicklung wurde beobachtet), wurden nach der Aufreinigung tatsächlich die 1-Pyrazoline als Produkte isoliert. Diese Verbindungen kçnnen durch UV-C-Bestrahlung (l = 254 nm) in die ursprünglich gezeigten Cyclopropane überführt werden. [1] Die entsprechenden Strukturen und Ausbeuten sind in der hier gezeigten Fassung von Schema 5und in den revidierten Hintergrundinformationen korrigiert. Alle Autoren entschuldigen sich fürdiese Fehlinterpretation der Charakterisierungsdaten und alle daraus folgenden Unannehmlichkeiten. Während das Cyclopropan 5e in 53 %Ausbeute (2.1:1 dr) isoliert wurde, ließ sich das entsprechende 1-Pyrazolin interessanterweise auch im 1 H-NMR-Spektrum der Reaktionsmischung nachweisen (> 15 %). Da alle in der Zuschrift beschriebenen Reaktionen ohne besondere Maßnahmen zum Lichtausschluss ausgeführt wurden, wurde diese Umsetzung mit einem strikt lichtgeschützten Auffanggefäßwiederholt. Dabei nahm die Menge an Pyrazolin im 1 H-NMR-Spektrum der Reaktionsmischung deutlich zu (~50 %), was darauf hindeutet, dass sichtbares Licht die Stickstoffabspaltung und Bildung der gewünschten Cyclopropane in bestimmten Fällen induzieren kann. Die Autoren bitten, diese Fehler zu entschuldigen. Sie danken Professor Szymon Buda (Jagiellonen-Universität) fürd en Hinweis sowie Professor Christopher Moody (University of Nottingham), der sie auf die falsche Strukturformel für 3k aufmerksam machte.

show abstract

“…Previous methodologies to oxidize benzophenone-derived hydrazones often require stoichiometric amounts of transition metals, such as Ag 2 O, 54 or toxic HgO 55 and Pb(OAc) 2 . 56 Several efforts have been put forth by chemists to discover greener alternatives to these metals.…”

Section: Short Review Syn Thesismentioning

confidence: 99%

Cyclopropanation Reactions of Semi-stabilized and Non-stabilized Diazo Compounds

Allouche¹,

Charette²

2019

Synthesis

View full text Add to dashboard Cite

The cyclopropane ring is present in a large number of bioactive molecules as its incorporation often greatly alters their physiochemical properties. The synthesis of such motif is therefore of interest. Diazo compounds are versatile and powerful reagents that can be used in a broad range of reactions, including cyclopropanation processes. However, in case of unstable diazo reagents such as the donor-substituted variants, their inherent toxicity and instability have hampered their effective synthesis and utilization. Herein, we report the recent advances devoted to the safe and facile production of these potentially hazardous species and their subsequent application in cyclopropanation reactions, allowing the synthesis of more complex cyclopropylated motifs.1 Introduction2 Halomethylmetal-Mediated Cyclopropanations3 Cyclopropanations through Metallic- or Free Carbenes3.1 Transition-Metal-Catalyzed Decomposition of Diazo Compounds3.2 Metal-Free Decomposition of Diazo Compounds4 Michael Induced Ring Closure (MIRC) Reactions4.1 Sulfur Ylides4.2 1,3-Dipolar Cycloadditions5 Conclusion

show abstract

The Use of Silver Oxide in the Preparation of Diaryldiazomethanes

Cited by 49 publications

References 0 publications

Safe and Facile Access to Nonstabilized Diazoalkanes Using Continuous Flow Technology

Safe and Facile Access to Nonstabilized Diazoalkanes Using Continuous Flow Technology

Safe and Facile Access to Nonstabilized Diazoalkanes Using Continuous Flow Technology

Cyclopropanation Reactions of Semi-stabilized and Non-stabilized Diazo Compounds

Contact Info

Product

Resources

About