- Vilsmeier formylation of hydrazones and semicarbazones derived from alkyl, benzyl, and cycloalkyl methyl ketones
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Formylation of ten accessible phenylhydrazones and semicarbazones derived from alkyl, benzyl, and cycloalkyl methyl ketones with the complex of POCl 3 with dimethylformamide was studied. Depending on the electronic and steric structure of the substrates, the reaction yields 1-phenyl- or 1-unsubstituted 3,4-dialkyl-, 3-alkyl-4-aryl-, or 3-alkyl-4-formylpyrazoles. These compounds can be readily oxidized into the corresponding carboxylic acids. 2005 Pleiades Publishing, Inc.
- Lebedev,Lebedeva,Sheludyakov,Kovaleva,Ustinova,Kozhevnikov
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Read Online
- Shaken, not stirred: a schools test for aldehydes and ketones
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A schools test for aldehydes and ketones in water at room temperature using test tubes has been developed in this laboratory using either phenylhydrazine hydrochloride or phenylhydrazine hydrochloride with NaOAc . 3H2O. The role of one equivalent of a strong or weak acid which catalyses the reaction is discussed.
- Plater, M John
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p. 104 - 107
(2019/11/22)
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- High-Throughput Mass Spectrometry Screening Platform for Discovering New Chemical Reactions under Uncatalyzed, Solvent-Free Experimental Conditions
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A gas-phase high-throughput reaction screening platform was developed for the first time to study chemical structures of closely related functional groups and for the discovery of novel organic reaction pathways. Experiments were performed using the contained atmospheric pressure chemical ionization (APCI) source that enabled nonthermal, nonequilibrium plasma chemistry to be monitored by mass spectrometry (MS) in real time. This contained-APCI MS platform allowed an array of reagents to be tested, resulting in the studies of multiple gas-phase reactions in parallel. By exposing headspace vapor of the selected reagents to corona discharge, solvent-free Borsche-Drecsel cyclization reaction, Katritzky chemistry, and Paal-Knorr pyrrole synthesis were examined in the gas phase, outside the high vacuum environment of the mass spectrometer. A new radical-mediated hydrazine coupling reaction was also discovered, which provided a selective pathway to synthesize secondary amines without using a catalyst. The mechanisms of these atmospheric pressure gas-phase reactions were explored through the direct capture of intermediates and via comparison with the corresponding bulk solution and droplet-phase reactions.
- Kulyk, Dmytro S.,Amoah, Enoch,Badu-Tawiah, Abraham K.
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p. 15025 - 15033
(2020/12/01)
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- Phenylsilane as an effective desulfinylation reagent
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The reduction using phenylsilane in a KOH-catalyzed system was applied successfully to the conversion of sulfinyl-substituted cyclopropylcarboxylates into the corresponding alcohols. The presence of sulfinyl substituents in the α-position to the carboxylate group caused a desulfinylation product formation with full regio- and stereoselectivity, instead of a carbonyl group reduction. Investigations performed on different α-sulfinylcarbonyl compounds revealed that phenylsilane treatment constitutes a regiospecific method for the desulfinylation of a-sulfinylesters; for corresponding ketones the reaction course depends on the character of the carbonyl group.
- Midura, Wanda H.,Rzewnicka, Aneta,Krysiak, Jerzy A.
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supporting information
p. 1513 - 1517
(2017/08/14)
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- Fast alpha nucleophiles: Structures that undergo rapid hydrazone/oxime formation at neutral pH
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Hydrazones and oximes are widely useful structures for conjugate formation in chemistry and biology, but their formation can be slow at neutral pH. Kinetics studies were performed for a range of structurally varied hydrazines, and a surprisingly large variation in reaction rate was observed. Structures that undergo especially rapid reactions were identified, enabling reaction rates that rival orthogonal cycloaddition-based conjugation chemistries.
- Kool, Eric T.,Crisalli, Pete,Chan, Ke Min
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supporting information
p. 1454 - 1457
(2014/04/03)
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- Fast hydrazone reactants: Electronic and acid/base effects strongly influence rate at biological pH
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Kinetics studies with structurally varied aldehydes and ketones in aqueous buffer at pH 7.4 reveal that carbonyl compounds with neighboring acid/base groups form hydrazones at accelerated rates. Similarly, tests of a hydrazine with a neighboring carboxylic acid group show that it also reacts at an accelerated rate. Rate constants for the fastest carbonyl/hydrazine combinations are 2-20 M-1 s-1, which is faster than recent strain-promoted cycloaddition reactions.
- Kool, Eric T.,Park, Do-Hyoung,Crisalli, Pete
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supporting information
p. 17663 - 17666
(2014/01/06)
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- Synthesis and in vitro anti-tumor activity of new oxadiazole thioglycosides
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A facile, convenient and high yielding synthesis of novel thioglycosides incorporating 1,3,4-oxadiazole, triazole and or triazine moieties from readily available starting materials has been described. The key step of this protocol is the formation of 3-isobutyl-1-phenyl-1H-pyrazole-4-carbaldehyde (3) via condensation between methyl iso-butyl ketone and phenylhydrazine followed by application of Vilsmeier-Haack reaction. 3 was converted either to 1,3,4-oxadiazole derivative or condensed with O-aminothiols to give the bases 8, 19 and 20 in good yields, respectively. The aglycons 8, 19, and 20 were coupled with different activated halosugars in the presence of basic medium. Pharmacological evaluation of compounds 8, 14, 16 and 22 in vitro against 2-cell lines MCF-7 (breast) and HEPG2 (liver) revealed them to possess high anti-tumor activities with IC50 values ranging from 2.67-20.25 (μg/mL) for breast cell line (MCF-7) and 4.62-43.6 (μg/mL) for liver cell line (HEPG2). None of the tested compounds exhibited any toxicity in doses up to 500 mg kg-1 of the animal body weight.
- Abu-Zaied,El-Telbani,Elgemeie,Nawwar
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experimental part
p. 229 - 235
(2011/02/27)
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- Electrochemical formation of methoxy- and cyano(phenylazo)alkanes from aldehyde and ketone phenylhydrazones
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Several aldehyde and ketone phenylhydrazones were electrooxidized in MeOH. Electrooxidation in the presence of KI or tetraethylammonium p-toluenesulfonate as the supporting electrolyte afforded the corresponding methoxy(phenylazo)alkanes, whereas electrooxidation in the presence of KI, NaCN, and HOAc afforded the cyano(phenylazo)alkanes.
- Okimoto, Mitsuhiro,Takahashi, Yukio,Kakuchi, Toyoji
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p. 2057 - 2063
(2007/10/03)
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- Benzothiadiphosphole as phosphorus donating reagent for a new route to 2H-1,2,3-diazaphosphole derivates
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Conjugated azoalkenes 2 react at reflux toluene with fused benzothiadiphosphole 1 (or 4) to give the diazaphosphole 3 in 25-52% yields. With this route it is possible to isolate the so far unknown 3a which is difficult to obtain in other reported conditions. The P atom involved in this cydoaddition is the one between the two S atoms.
- Baccolini,Orsolan,Mezzina
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p. 447 - 450
(2007/10/02)
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- Regioselective Indolization of Unsymmetrical Phenylhydrazones by Reaction, at Room Temperature, with PCl3
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Unsymmetrical ketone phenylhydrazones (1) (R1 ae R2) react with PCl3, at room temperature to give predominantly one, (2), of the two possible 2,3-disubstituted indoles in good to excellent overall yield.When the R1 and R2 groups are very different (R1 = Ph or Me; R2 = alkyl or H) the reaction is highly regioselective leading to exclusive or prevalent formation of the corresponding 3-R1 indoles (2), whereas when R1 and R2 are very similar (R1, R2 = alkyl chains) the regioselectivity is decreased and the indole having the shorter chain in the 3-position predominates, but only slightly.Inspection of the results enables the direction of indolization to be predicted and the positions of the substituents in the 2,3-disubstituted indoles to be assigned with certainty, features not inherent in the classical Fischer indolization.
- Baccolini, Graziano,Bartoli, Giuseppe,Marotta, Emanuela,Todesco, Paolo E.
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p. 2695 - 2697
(2007/10/02)
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- ALKALINE ISOMERIZATION OF PHENYLHYDRAZONES TO ALKYLPHENYLDIIMIDES
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When solutions pf phenylhydrazones in tri- or tetraethylene glycol are heated in the presence of the corresponding sodium glycolate, they undergo isomerization to alkylphenyldiimidates.There is a marked decrease in the isomerization rate in the transition from the hydrazones of aldehydes to the hydrazones of ketones.With the phenylhydrazones of ketones the reaction takes place almost unambiguously, but in the case of hydrazones of aldehydes it is complicated to an appreciable extent by side processes such as indolization and aminonitrile cleavage.
- Kuznetsov, M.A.,Suvorov, A.A.
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p. 1684 - 1691
(2007/10/02)
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- Effect of steric factors in the heterogeneous-catalytic E. Fischer reaction. XII. Heterogeneous-catalytic E. Fischer reaction
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The effect of steric factors on the indolization under the conditions of heterogeneous catalysis was investigated for the case of a series of N-alkyl- and N-aryl-substituted phenylhydrazones of methyl ethyl ketone.There is a definite correlation between the stereochemical structure of the arylhydrazones and their ability to undergo cyclization to the corresponding indole.
- Suvorov, N. N.,Shkil'kova, V. N.,Podkhalyuzina N. Ya.
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p. 649 - 652
(2007/10/02)
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