- Conversions of hydrazones to diazo compounds by n-butyllithium and azidotris(diethylamino)phosphonium bromide
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Lithium hydrazonides, prepared by reactions of hydrazones with n-BuLi/hexane in THF at -78°C, are converted by azidotris(diethylamino)phosphonium bromide in THF at ~0°C efficiently, rapidly, and safely to their corresponding diazo compounds along with tri
- McGuiness, Mark,Shechter, Harold
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Read Online
- A Novel Synthesis of Arylsulfonyl Hydrazine Derivatives Via the Reaction of Arylsulfonyl Hydrazone Salts and Hydrazonoyl Chlorides
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An efficient method for the synthesis of arylsulfonyl hydrazines and diazo compounds via arylsulfonyl hydrazone salts is described. The reaction was performed in DMF using hydrazonoyl chlorides and sodium arylsulfonyl hydrazones, which were easily prepare
- Khalili, Gholamhossein
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Read Online
- alpha-aryl or alkyl substituted borane adduct, preparation method and applications thereof
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The invention relates to an alpha-aryl or alkyl substituted borane adduct, a preparation method and applications thereof, specifically to preparation of an alpha-aryl or alkyl substituted borane adduct by carrying out a reaction on hydrazone as an unstabl
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Paragraph 0305-0308; 0310-0313; 0315
(2020/01/25)
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- Umpolung-like Cross-coupling of Tosylhydrazones with 4-Hydroxy-2-pyridones under Palladium Catalysis
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Tosylhydrazones under palladium catalysis were found to perform cross-coupling reactions with 4-hydroxy-2-pyridones. The umpolung-like reactivity, between the α-carbon of tosylhydrazone and the 3-position of the heterocycle, which is observed in the obtai
- Katsina, Tania,Papoulidou, Kyriaki Eleni,Zografos, Alexandros L.
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supporting information
p. 8110 - 8115
(2019/10/11)
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- Safe and Facile Access to Nonstabilized Diazoalkanes Using Continuous Flow Technology
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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.
- Rullière, Pauline,Benoit, Guillaume,Allouche, Emmanuelle M. D.,Charette, André B.
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p. 5777 - 5782
(2018/05/14)
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- Copper-Catalyzed Formal Carbene Migratory Insertion into Internal Olefinic C=C Bonds with N-Tosylhydrazones to Access Iminofuran and 2(3H)-Furanone Derivatives
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Efficient copper-catalyzed formal carbene migratory insertion into the olefinic C=C bonds of internal olefins, that is, α-oxo ketene N,S-acetals, has been achieved by means of N-tosylhydrazones of ketones as the carbene precursors. Iminofuran derivatives
- Huang, Fei,Liu, Zhuqing,Wang, Quannan,Lou, Jiang,Yu, Zhengkun
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supporting information
p. 3660 - 3663
(2017/07/15)
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- Fluorogenic Strain-Promoted Alkyne-Diazo Cycloadditions
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Fluorogenic reactions, in which non- or weakly fluorescent reagents produce highly fluorescent products, are attractive for detecting a broad range of compounds in the fields of bioconjugation and material sciences. Herein, we report that a dibenzocyclooctyne derivative modified with a cyclopropenone moiety (Fl-DIBO) can undergo fast strain-promoted cycloaddition reactions under catalyst-free conditions with azides, nitrones, nitrile oxides, as well as mono- and disubstituted diazo-derivatives. Although the reaction with nitrile oxides, nitrones, and disubstituted diazo compounds gave cycloadducts with low quantum yield, monosubstituted diazo reagents produced 1H-pyrazole derivatives that exhibited an approximately 160-fold fluorescence enhancement over Fl-DIBO combined with a greater than 10 000-fold increase in brightness. Concluding from quantum chemical calculations, fluorescence quenching of 3H-pyrazoles, which are formed by reaction with disubstituted diazo-derivatives, is likely due to the presence of energetically low-lying (n,π?) states. The fluorogenic probe Fl-DIBO was successfully employed for the labeling of diazo-tagged proteins without detectable background signal. Diazo-derivatives are emerging as attractive reporters for the labeling of biomolecules, and the studies presented herein demonstrate that Fl-DIBO can be employed for visualizing such biomolecules without the need for probe washout.
- Friscourt, Frédéric,Fahrni, Christoph J.,Boons, Geert-Jan
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p. 13996 - 14001
(2015/09/28)
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- Cyclopropanation using flow-generated diazo compounds
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We have devised a room temperature process for the cyclopropanation of electron-poor olefins using unstabilised diazo compounds, generated under continuous flow conditions. This protocol was applied to a wide range of different diazo species to generate f
- Roda, Nuria M.,Tran, Duc N.,Battilocchio, Claudio,Labes, Ricardo,Ingham, Richard J.,Hawkins, Joel M.,Ley, Steven V.
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p. 2550 - 2554
(2015/11/17)
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- Straightforward reductive esterification of carbonyl compounds with carboxylic acids through tosylhydrazone intermediates
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The reaction of carboxylic acids with tosylhydrazones in basic media gives rise to the corresponding esters through an O-H insertion reaction in the in situ generated diazo compound. The process is operationally very simple, catalyst free, and very general with regard to the structure of both coupling partners. In particular, the esterification can be accomplished by employing tosylhydrazones derived from enolizable carbonyl compounds. Considering the ready availability of tosylhydrazones from carbonyl compounds, this reaction can be visualized as a reductive esterification of carbonyl compounds.
- Garcia-Munoz, Angel-Humberto,Tomas-Gamasa, Maria,Perez-Aguilar, M. Carmen,Cuevas-Yanez, Erick,Valdes, Carlos
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supporting information; experimental part
p. 3925 - 3928
(2012/08/28)
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- First direct detection of 2,3-dimethyl-2,3-diphenylcyclopropanone
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(Chemical Equation Presented) 3,5-Dihydro-3,5-dialkyl-3,5-diaryl-4H- pyrazol-4-ones stimulate interest as potential precursors for 2,3-diarylcyclopropanones. Photoreactions of trans-3,5-dihydro-3,5-dimethyl-3,5- diphenyl-4H-pyrazol-4-one were studied by c
- Moiseev, Andrey G.,Abe, Manabu,Danilov, Evgeny O.,Neckers, Douglas C.
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p. 2777 - 2784
(2008/02/03)
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- Diazo preparation via dehydrogenation of hydrazones with "activated" DMSO
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We report that "activated" dimethyl sulfoxide efficiently dehydrogenates hydrazones to the respective diazo species at -78°C. Under optimized conditions, triethylamine hydrochloride is removed quantitatively by vacuum filtration to provide solutions of diazo compounds. Stable diazo species can be isolated in high yield, or alternatively, the direct treatment of these solutions with carboxylic acids provides esters.
- Javed, Muhammad I.,Brewer, Matthias
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p. 1789 - 1792
(2008/02/02)
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- The β-heteroatom effect on carbenes
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The β-thiophosphinoyl carbene PhCCH2P(S)Ph2 (5) has been prepared by irradiation of the corresponding diazo compound. The relative rates for insertion into the OH bond of methanol and for addition to the double bond of 2-methyl-2-but
- Lambert, Joseph B.,Liu, Xiaoyang
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p. 9989 - 9996
(2007/10/03)
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- Advantageous Syntheses of Diazo Compounds by Oxidation of Hydrazones with Lead Tetraacetate in Basic Environments
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Varied sensitive diazo compounds 3 are produced efficiently and safely in 3-6 g quantities by oxidation (eq 1) of hydrazones 1 at -78 deg C with lead tetraacetate (2) in triethylamine/chloroform, N-methylmorpholine/dimethylformamide, tetramethylguanidine (8)/dimethylformamide, and tetramethylguanidine/methylene chloride, respectively, upon use of appropriate workup and handling techniques.New and improved nonhazardous procedures have been developed for preparing and handling hydrazones 1 from aldehydes and ketones in reactions with excess hydrazine.
- Holton, Terrence L.,Shechter, Harold
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p. 4725 - 4729
(2007/10/02)
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- A significant barrier to 1,2 hydrogen migration in singlet 1-phenylethylidene. A laser flash photolysis study
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Laser flash photolysis of 1-phenyldiazoethane in heptane releases 1-phenylethylidene which can be intercepted with pyridine to form an ylide (λmax> = 475 nm). Oxygen trapping experiments indicate that relaxation of singlet 1-phenylethylidene to
- Sugiyama, Michelle H.,Celebi, Sol,Platz, Matthew S.
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p. 966 - 973
(2007/10/02)
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- CYCLOADDITIONS OF DISUBSTITUTED DIAZO COMPOUNDS TO P-CHLORO(BISTRIMETHYLSILYL) METHYLENE PHOSPHINE.
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Disubstituted diazo compounds rapidly add to P-chloro (bistrimethylsilyl) methylene phosphine at low temperature. 1H, 31P and 13C NMR allow the characterization of the resulting cycloadducts and the establisment of the stereochemistry of the resulting cycloadducts which are potential precursors of ?3λ5 bis methylene phosphorane by nitrogen extrusion.
- Thoraval, J. Y.,Nagai, W.,Yeung Lam Ko, Y. Y. C.,Carrie, R.
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p. 3859 - 3868
(2007/10/02)
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- trans-2,3-Di-tert-butylthiirane 1,1-Dioxide and 2,5-Di-tert-butyl-2,5-dihydro-1,3,4-thiadiazole 1,1-Dioxides from tert-Butyldiazomethane and Sulfur Dioxide. Solvent Effects and Mechanisms of the Staudinger-Pfenninger-Reaction
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When allowed to react with sulfur dioxide tert-butyldiazomethane formed not only trans-di-tert-butylthiirane 1,1-dioxide (3) but also the diastereomeric 2,5-dihydro-1,3,4-thiadiazole 1,1-dioxides 7e which under base-catalysis rearranged to the 2,3-dihydro-1,3,4-thiadiazole 1,1-dioxide 11.The structures were deduced from IR, UV, and 1H-NMR-spectra, and from the products obtained after loss sulfur dioxide.Whereas increase of the solvent polarity favoured 3 over 7e, the diastereomer ratio cis-7e/trans-7e remained virtually unaffected.The ratio of thiirane 1,1-dioxide 3 to dihydrothiadiazole 1,1-dioxides did not depend on whether the intermediate tert-butylsulfene 6e had been generated from 5e and sulfur dioxide or from 2,2-dimethylpropane sulfonylchloride (14) and triethylamine.In contrast to reports in the literature, the reaction of the phenyldiazoalkanes 5f and 5h with sulfur dioxide afforded cis/trans ratios of the thiirane 1,1-dioxides 9f and 9h, respectively, which were only slightly influenced by the solvent.Apparently, the dihydrothiadiazole 1,1-dioxides 7 and hence their decomposition products, the azines 8 (as far as these do not arise from the direct decomposition of the diazo compounds), are the result of a cycloaddition between the diazoalkane 5 and the sulfene 6.In contrast, the thiirane 1,1-dioxides 9 seem to originate via the zwitterions 20 the formation of which is favoured over the cycloaddition by solvents of high polarity, by the presence of aryl substituents at the sulfene, as well as by the lack of alkyl groups.The dichotomy in the behaviour of sulfenes towards diazoalkanes can be traced back to the existence of two low-lying sulfene MO's, only one of which exhibits ?-symmetry.
- Quast, Helmut,Kees, Frieder
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p. 787 - 801
(2007/10/02)
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