- Synthetic Scope of Br?nsted Acid-Catalyzed Reactions of Carbonyl Compounds and Ethyl Diazoacetate
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The comprehensive study of the reactions of carbonyl compounds and ethyl diazoacetate in the presence of a Br?nsted acid catalyst is described. In result, a broad range of 3-oxo-esters were synthesized from a variety of ketones and aliphatic aldehydes by 1,2-aryl/alkyl/hydride shift. Aryl-methyl ketones produced only aryl-migrated products, whereas other ketones yielded a mixture of products. For diaryl ketones, the identity of two inseparable migrated products was confirmed by two-dimensional NMR spectroscopy.
- Rahaman, Mizzanoor,Ali, M. Shahnawaz,Jahan, Khorshada,Hinz, Damon,Belayet, Jawad Bin,Majinski, Ryan,Hossain, M. Mahmun
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p. 6138 - 6147
(2021/05/06)
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- Synthesis of Dithiolethiones and Identification of Potential Neuroprotective Agents via Activation of Nrf2-Driven Antioxidant Enzymes
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Oxidative stress is implicated in the pathogenesis of a wide variety of neurodegenerative disorders, and accordingly, dietary supplement of exogenous antioxidants or/and upregulation of the endogenous antioxidant defense system are promising for therapeutic intervention or chemoprevention of neurodegenerative diseases. Nrf2, a master regulator of the cellular antioxidant machinery, cardinally participates in the transcription of cytoprotective genes against oxidative/electrophilic stresses. Herein, we report the synthesis of 59 structurally diverse dithiolethiones and evaluation of their neuroprotection against 6-hydroxydopamine-or H2O2-induced oxidative damages in PC12 cells, a neuron-like rat pheochromocytoma cell line. Initial screening identified compounds 10 and 11 having low cytotoxicity but conferring remarkable protection on PC12 cells from oxidative-mediated damages. Further studies demonstrated that both compounds upregulated a battery of antioxidant genes as well as corresponding genes' products. Significantly, silence of Nrf2 expression abolishes cytoprotection of 10 and 11, indicating targeting Nrf2 activation is pivotal for their cellular functions. Taken together, the two lead compounds discovered here with potent neuroprotective functions against oxidative stress via Nrf2 activation merit further development as therapeutic or chemopreventive candidates for neurodegenerative disorders.
- Bai, Feifei,Fang, Jianguo,Song, Zi-Long,Zhang, Baoxin
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p. 2214 - 2231
(2020/03/06)
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- One-Pot Reaction of Carboxylic Acids and Ynol Ethers for the Synthesis of β-Keto Esters
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An one-pot reaction of carboxylic acids and ynol ethers for the synthesis of β-keto esters has been developed. Under promotion of Ag2O, various carboxylic acids and ynol ethers could transform to α-acyloxy enol esters, which undergo a following DMAP-catalyzed rearrangement to deliver β-keto esters rapidly. This method provides a direct approach to β-keto esters from carboxylic acids without any preactivation. The protocol features mild reaction conditions, broad substrate scope, and the products could be transformed to an array of compounds.
- Zeng, Linwei,Lai, Zhencheng,Cui, Sunliang
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p. 14834 - 14841
(2018/12/14)
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- Enantioselective Oxidative Rearrangements with Chiral Hypervalent Iodine Reagents
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A stereoselective hypervalent iodine-promoted oxidative rearrangement of 1,1-disubstituted alkenes has been developed. This practically simple protocol provides access to enantioenriched α-arylated ketones without the use of transition metals from readily
- Brown, Michael,Kumar, Ravi,Rehbein, Julia,Wirth, Thomas
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supporting information
p. 4030 - 4035
(2016/03/16)
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- A copper-mediated oxidative coupling route to 3H- and 1H-indoles from N-aryl-enamines
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A facile copper(II)-mediated C-H bond oxidation and C-C bond formation procedure has been applied to the synthesis of indole derivatives. Intramolecular oxidative coupling of 3,3-disubstituted enamines proceeded using a non-expensive and air-stable copper
- Drouhin, Pauline,Taylor, Richard J. K.
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supporting information
p. 2333 - 2336
(2015/04/22)
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- Palladium-catalyzed Cross-coupling of aryl iodides with β-trimethylsiloxy-α-diazoesters: A novel approach toward β-keto-α-arylesters
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Palladium-catalyzed cross-coupling of β-trimethylsiloxy- α-diazoesters with aryl iodides provides a new approach to β-keto-α-arylesters. It is shown that the β-trimethylsiloxy group can significantly suppress the direct 1,2-hydride shift from palladium carbene.
- Shu, Zhibin,Zhang, Ji,Zhang, Yan,Wang, Jianbo
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scheme or table
p. 1009 - 1011
(2011/12/05)
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- Base-free two-step synthesis of 1,3-diketones and β-ketoesters from α-diazocarbonyl compounds, trialkylboranes, and aromatic aldehydes
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We describe a convergent, base-free two-step synthesis of 1,3-diketones and β-ketoesters from α-diazocarbonyl compounds, trialkylboranes, and aromatic aldehydes in a three-component process. The synthetic potential of this protocol was underscored by the
- Sanchez-Carmona, Miguel A.,Contreras-Cruz, David A.,Miranda, Luis D.
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p. 6506 - 6508
(2011/11/05)
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- Dynamic kinetic resolution in the asymmetrie synthesis of β-amino acids by organocatalytic reduction of enamines with trichlorosilane
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A new methodology based on the organocatalytic asymmetric hydrosilylation of enamines that allows a direct access to a range of β3 and β2.3-amino acid derivatives was presented. The results show a successful reduction of aromatic substrates, a sterically more hindered ortho-substituted derivatives, and the thiophenyl analogue exhibiting lower reactivity. Fast enamine-imine equilibration is crucial as imines are chiral but racemic, while α-alkyl β-amino acids can be accessed by the symmetrical Mannich reaction. The α-alkyl derivatives have relative and absolute configuration due to their reduction with LiAlH4 into a known amino alcohols. Predominant formation of the anti isomer in 3o is consistent with conformation of the imine intermediate in the catalytic reduction.
- Malkov, Andrei V.,Stoncius, Sigitas,Vrankova, Kvetoslava,Arndt, Matthias,Kocovsky, Pavel
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supporting information; experimental part
p. 8082 - 8085
(2009/09/29)
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- Studies in N-amino-3-aza Cope rearrangements
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The first examples of a N-amino-3-aza Cope rearrangement as well as the first N-amino-anion 3-aza Cope rearrangement are reported. These occur in good to excellent yields and in short reaction times.
- Glória, Paulo M.C.,Prabhakar, Sundaresan,Lobo, Ana M.
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scheme or table
p. 7355 - 7357
(2009/05/07)
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- Pyrazole antimicrobial agents
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The present invention provides pyrazole and pyrazolone derivatives. Preferred compounds of the invention are useful as RNA polymerase inhibitors. Further preferred compounds of the invention are useful as antimicrobial agents.
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- Photogeneration of Highly Electrophilic Benzoylketene from Dibenzoyldiazomethane in Aqueous Solvents: Reaction with Amino Acids and DNA Cleavage
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Photoirradiation of dibenzoyldiazomethane in the presence of amino acid derivatives in aqueous solutions efficiently produced the addition products through a reaction with photogenerated benzoylketene.Efficient DNA cleavage was observed with a dibenzoyldiazomethane derivative, possessing a cationic side chain under photoirradiation conditions.
- Nakatani, Kazuhiko,Shirai, Junya,Tamaki, Ryo,Saito, Isao
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p. 5363 - 5366
(2007/10/02)
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- CATALYTIC AND THERMAL DECOMPOSITION OF 2-DIAZO-1,3-DIPHENYL-1,3-PROPANEDIONE IN DIMETHYL HYDROGEN PHOSPHITE AND O,O-DIETHYL HYDROGEN PHOSPHOROTHIOITE
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By the CuII-catalyzed decomposition of 2-diazo-1,3-diphenyl-1,3-propanedione in dimethyl hydrogen phosphite dimethyl (dibenzoylmethyl)phosphonate is obtained.By means of IR and PMR spectroscopy it was shown that in the crystalline state the phsphonate exists in the diketo form, but in CDCl3 solution it is an equilibrium mixture of keto and ionized forms.
- Arbuzov, B. A.,Polozov, A. M.,Polezhaeva, N. A.
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p. 1351 - 1354
(2007/10/02)
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- "Wolf and lamb" reactions: Equilibrium and kinetic effects in multipolymer systems
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Two reagents reacting avidly with each other in solution are rendered mutually inactive by attaching each to a separate batch of insoluble polymer. Two-stage reactions in which a soluble reagent reacts first with one polymeric reagent and the product with the second polymeric reagent afford advantages over analogous reactions in solution. In acylation reactions of carbon acids, the simultaneous use of a polymeric strong base and a polymeric acylating reagent proved to be superior to the use of soluble reagents, both for bringing about quantitative acylations and for coping with undesirable side reactions. New polymeric strong bases were prepared: polymeric trityllithium, para-substituted trityllithium polymers, and polymeric lithium diisopropylamide. Active esters of polymeric o-nitrophenol and N-1-hydroxybenzotriazole were used as acylation reagents. The scope and limitation of these reactions and their application to general multiphase systems are discussed.
- Cohen,Kraus,Patchornik
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p. 7620 - 7629
(2007/10/02)
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