- Ruthenium catalyzed β-selective alkylation of vinylpyridines with aldehydes/ketonesviaN2H4mediated deoxygenative couplings
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Umpolung (polarity reversal) tactics of aldehydes/ketones have greatly broadened carbonyl chemistry by enabling transformations with electrophilic reagents and deoxygenative functionalizations. Herein, we report the first ruthenium-catalyzed β-selective alkylation of vinylpyridines with both naturally abundant aromatic and aliphatic aldehyde/ketonesviaN2H4mediated deoxygenative couplings. Compared with one-electron umpolung of carbonyls to alcohols, this two-electron umpolung strategy realized reductive deoxygenation targets, which were not only applicable to the regioselective alkylation of a broad range of 2/4-alkene substituted pyridines, but also amenable to challenging 3-vinyl and steric-embedded internal pyridines as well as their analogous heterocyclic structures.
- Lv, Leiyang,Li, Chao-Jun
-
p. 2870 - 2875
(2021/03/14)
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- Addition reactions of organic carbanion equivalents via hydrazones in water
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The addition of organometallic reagents to unsaturated bonds is one of the most powerful tools for carbon–carbon bond formations. Alkylation through organometallic reagents requires stoichiometric quantity of metal and tedious anhydrous operation in most cases. Here, we report “umpolung” nucleophilic additions of hydrazones to Michael acceptors, carbonyls and imines in water. Under the catalysis of ruthenium(II), the addition reactions could be carried out in pure water to provide various alkylation products in moderate to good yields.
- Wang, Yi-Zhan,Liu, Qi,Cheng, Liang,Yu, Song-Chen,Liu, Li,Li, Chao-Jun
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supporting information
(2021/01/11)
-
- DNA interaction, anticancer, antibacterial, ROS and lipid peroxidation studies of quinoxaline based organometallic Re(I) carbonyls
-
Hetero mononuclear rhenium(I) complexes (I-V) using ligands (L1-L5) [L1-L5 = 11-((2-chlorobenzylidene)hydrazono)-11H-indeno[1,2-b]quinoxaline (L1), 8-methyl-11-((4-methyl-benzylidene)hydrazono)-11H-indeno[1,2-b]quinoxaline (L2), 11-((4-bromobenzylidene) hydrazono)-8-nitro-11H-indeno[1,2-b]quinoxaline (L3), 11-((4-bromobenzylidene) hydrazono)-8-chloro-11H-indeno[1,2-b]quinoxaline (L4), 8-bromo-11-((4-fluorobenzylidene) hydrazono)-11H-indeno[1,2-b]quinoxaline (L5)] were synthesized and characterized by spectroscopic method. All the synthesized compounds have biological importance. DNA interaction studies gave information about the modes of binding and the nucleolytic efficiency of compounds. The binding of the rhenium complexes to Herring sperm DNA (HS DNA) was monitored by UV–visible spectroscopy, viscosity measurements, and molecular docking studies; groove binding was suggested as the most possible mode. The DNA-complexes binding strength was measured in terms of intrinsic binding constants. In vivo and In vitro cytotoxicity against the eukaryotic and prokaryotic cells gave the toxic nature of the synthesized compounds. An antimicrobial study was carried out by estimating MIC (Minimum Inhibitory Concentration) against two Gram-positive (S. aureus, B. subtilis) and three Gram-negative (S. marcescens, P. aeruginosa, E. coli) bacteria. All synthesized complexes are biologically more active than the corresponding ligands. Complexes were having higher MDA and H2O2 production than ligands.
- Varma, Reena R.,Pandya, Juhee G.,Vaidya, Foram U.,Pathak, Chandramani,Dabhi, Ravi A.,Dhaduk, Milan P.,Bhatt, Bhupesh S.,Patel, Mohan N.
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- Palladium-Catalyzed Defluorinative Alkylation of gem-Difluorocyclopropanes: Switching Regioselectivity via Simple Hydrazones
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Conventional approaches for Pd-catalyzed ring-opening cross-couplings of gem-difluorocyclopropanes with nucleophiles predominantly deliver the β-fluoroalkene scaffolds (linear selectivity). Herein, we report a cooperative strategy that can completely switch the reaction selectivity to give the alkylated α-fluoroalkene skeletons (branched selectivity). The unique reactivity of hydrazones that enables analogous inner-sphere 3,3′-reductive elimination driven by denitrogenation, as well as the assistance of steric-embedded N-heterocyclic carbene ligand, are the key to switch the regioselectivity. A wide range of hydrazones derived from naturally abundant aryl and alkyl aldehydes are well applicable, and various gem-difluorocyclopropanes, including modified pharmaceutical and biological molecules, can be efficiently functionalized with high value alkylated α-fluorinated alkene motifs under mild conditions.
- Lv, Leiyang,Li, Chao-Jun
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supporting information
p. 13098 - 13104
(2021/05/03)
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- Submonomer synthesis of peptoids containingtrans-inducingN-imino- andN-alkylamino-glycines
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The use of hydrazones as a new type of submonomer in peptoid synthesis is described, giving access to peptoid monomers that are structure-inducing. A wide range of hydrazones were found to readily react with α-bromoamides in routine solid phase peptoid submonomer synthesis. Conditions to promote a one-pot cleavage of the peptoid from the resin and reduction to the correspondingN-alkylamino side chains were also identified, and both theN-imino- andN-alkylamino glycine residues were found to favor thetrans-amide bond geometry by NMR, X-ray crystallography, and computational analyses.
- Davern, Carolynn M.,Ison, Elon A.,Lowe, Brandon D.,Proulx, Caroline,Rosfi, Adam
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p. 8401 - 8410
(2021/06/28)
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- Copper-Catalyzed Conjugate Addition of Carbonyls as Carbanion Equivalent via Hydrazones
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Copper-catalyzed conjugate addition is a classic method for forming new carbon-carbon bonds. However, copper has never showed catalytic activity for umpolung carbanions in hydrazone chemistry. Herein, we report a facile conjugate addition of hydrazone catalyzed by readily available copper complexes at room temperature. The employment of mesitylcopper(I) and electron-rich phosphine bidentate ligand is a key factor affecting reactivity. The reaction allows various aromatic hydrazones to react with diverse conjugated compounds to produce 1,4-adducts in yields of about 20 to 99%.
- Luo, Siyi,Peng, Marie,Querard, Pierre,Li, Chen-Chen,Li, Chao-Jun
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p. 13111 - 13117
(2021/09/18)
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- Switch in Selectivity for Formal Hydroalkylation of 1,3-Dienes and Enynes with Simple Hydrazones
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Controlling reaction selectivity is a permanent pursuit for chemists. Regioselective catalysis, which exploits and/or overcomes innate steric and electronic bias to deliver diverse regio-enriched products from the same starting materials, represents a powerful tool for divergent synthesis. Recently, the 1,2-Markovnikov hydroalkylation of 1,3-dienes with simple hydrazones was reported to generate branched allylic compounds when a nickel catalyst was used. As part of the effort, shown here is that a complete switch of Markovnikov to anti-Markovnikov addition is obtained by changing to a ruthenium catalyst, thus providing direct and efficient access to homoallylic products exclusively. Isotopic substitution experiments indicate that no reversible hydro-metallation across the metal-π-allyl system occurred under ruthenium catalysis. Moreover, this protocol is applicable to the regiospecific hydroalkylation of the distal C=C bond of 1,3-enynes.
- Li, Chao-Jun,Lv, Leiyang,Qiu, Zihang,Yu, Lin
-
supporting information
p. 6466 - 6472
(2020/03/13)
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- Structural studies of 2,5-disubstituted 1,3,4-thiadiazole derivatives from dithioesters under the mild condition: Studies on antioxidant, antimicrobial activities, and molecular docking
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A series of 2,5-disubstituted 1,3,4-thiadiazole was synthesized and evaluated for their antioxidant and molecular docking studies. These molecules were efficiently synthesized under mild and inexpensive starting material. Construction of these molecules developed using substituted aldehydes and substituted dithioesters in presence of NCS (N-Chorosuccinimide). The compounds 4a, 4b, 4c, 4f, and 4k showed good antibacterial and antioxidant activity among which, 4k possess excellent antibacterial and antioxidant activity. The results of antioxidant activity studies revealed that compound 4k manifested profound antioxidant potential. The molecular docking study was performed with respective newly synthesized compounds to ascertain the binding mode of 4k with respect to the critical proteins involved in biosynthesis and metabolic pathways.
- Gowda, Kemparaje,Kanchugarkoppal, Rangappa S.,Kempegowda, Mantelingu,Nagarakere, Sandhya C.,Rangappa, Shobith,Swarup, Hassan A.
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- Efficient Multigram Approach to Acetylenes and CF3-ynones Starting from Dichloroalkenes Prepared by Catalytic Olefination Reaction (COR)
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A novel approach to terminal acetylenes based on catalytic olefination reaction COR of arylaldehydes to form dichloroalkenes followed by treatment with nBuLi was elaborated. This method is atom economical and displays high yields and effectivity. The corresponding alkynes can be prepared in up to 97 % yield. One pot procedure towards CF3-ynones was elaborated to provide these products in up to 87 % yield starting from dichloroalkenes.
- Muzalevskiy, Vasiliy M.,Sizova, Zoia A.,Diusenov, Arstan I.,Shastin, Alexey V.,Nenajdenko, Valentine G.
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supporting information
p. 4161 - 4166
(2020/07/13)
-
- Palladium-Catalyzed Formal Hydroalkylation of Aryl-Substituted Alkynes with Hydrazones
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We have developed an unprecedented Pd-catalyzed formal hydroalkylation of alkynes with hydrazones, which are generated in situ from naturally abundant aldehydes, as both alkylation reagents and hydrogen donors. The hydroalkylation proceeds with high regio- and stereoselectivity to form (Z)-alkenes, which are more difficult to generate compared to (E)-alkenes. The reaction is compatible with a wide range of functional groups, including hydroxy, ester, ketone, nitrile, boronic ester, amine, and halide groups. Furthermore, late-stage modifications of natural products and pharmaceutical derivatives exemplify its unique chemoselectivity, regioselectivity, and synthetic applicability. Mechanistic studies indicate the possible involvement of Pd-hydride intermediates.
- Yu, Lin,Lv, Leiyang,Qiu, Zihang,Chen, Zhangpei,Tan, Ze,Liang, Yu-Feng,Li, Chao-Jun
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supporting information
p. 14009 - 14013
(2020/06/10)
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- Palladium-catalyzed hydroalkylation of methylenecyclopropanes with simple hydrazones
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A palladium-catalyzed hydroalkylation reaction of methylenecyclopropanes via highly selective C-C σ-bond scission was achieved under mild conditions, in which simple hydrazones served as carbanion equivalents. This method featured good functional group compatibility, affording high yields of C-alkylated terminal alkenes.
- Cao, Dawei,Chen, Zhangpei,Li, Chao-Jun,Lv, Leiyang,Yao, Jinzhong,Yu, Lin
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p. 10759 - 10763
(2020/10/26)
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- Nickel-catalyzed cross-coupling of umpolung carbonyls and alkyl halides
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An effective nickel-catalyzed cross-coupling of Umpolung carbonyls and alkyl halides was developed. Complementary to classical alkylation techniques, this reaction utilizes Umpolung carbonyls as the environmentally benign alkyl nucleophiles, providing an efficient and selective catalytic alternative to the traditional use of highly reactive alkyl organometallic reagents.
- Zhu, Dianhu,Lv, Leiyang,Qiu, Zihang,Li, Chao-Jun
-
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- Nickel-Catalyzed Cross-Coupling of Umpolung Carbonyls and Alkyl Halides
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An effective nickel-catalyzed cross-coupling of Umpolung carbonyls and alkyl halides was developed. Complementary to classical alkylation techniques, this reaction utilizes Umpolung carbonyls as the environmentally benign alkyl nucleophiles, providing an efficient and selective catalytic alternative to the traditional use of highly reactive alkyl organometallic reagents.
- Zhu, Dianhu,Lv, Leiyang,Qiu, Zihang,Li, Chao-Jun
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p. 6312 - 6322
(2019/05/24)
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- Denitrogenative Hydrotrifluoromethylation of Benzaldehyde Hydrazones: Synthesis of (2,2,2-Trifluoroethyl)arenes
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Reacting hydrazones of arylaldehydes with Togni's CF3-benziodoxolone reagent, in the presence of potassium hydroxide and cesium fluoride, induces a denitrogenative hydrotrifluoromethylation event to produce (2,2,2-trifluoroethyl)arenes. This novel reaction was tolerant to many electronically-diverse functional groups and substitution patterns, as well as naphthyl- and heteroaryl-derived substrates. Advantages of this process include the easy access to hydrazone precursors on a large scale, speed and operational simplicity, and being transition metal-free.
- Zhao, Zhensheng,Ma, Kevin C. Y.,Legault, Claude Y.,Murphy, Graham K.
-
supporting information
p. 11240 - 11245
(2019/08/20)
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- Umpolung cross-coupling of polyfluoroarenes with hydrazones: Via activation of C-F bonds
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An umpolung strategy for the cross-coupling of polyfluoroarenes with various substituted hydrazones to construct C(sp2)-C(sp3) bonds is developed. In this strategy, the C-F bond of polyfluoroarenes is cleaved and coupled with moisture- and air-stable hydrazones under mild conditions with good to excellent yields. This method provides a useful tool for synthesizing polyfluorinated pharmaceuticals and functional materials.
- Cao, Dawei,Pan, Pan,Zeng, Huiying,Li, Chao-Jun
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supporting information
p. 9323 - 9326
(2019/08/08)
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- Nickel-Catalyzed Regioselective Hydrobenzylation of 1,3-Dienes with Hydrazones
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Hydroalkylation of unsaturated hydrocarbons with unstabilized carbon nucleophiles is difficult and remains a major challenge. The disclosed examples so far have mainly focused on the involvement of heteroatom and/or stabilized carbon nucleophiles as efficient reaction partners. Reported here is an unprecedented regioselective nickel-catalyzed hydrobenzylation of 1,3-dienes with hydrazones, generated in situ from abundant aryl aldehydes and ketones and acting as both the sources of unstabilized carbanion equivalent and hydride. With this strategy, both terminal and sterically hindered internal dienes are hydroalkylated efficiently in a highly selective manner, thus providing a reliable catalytic method to construct challenging C(sp3)-C(sp3) bonds.
- Lv, Leiyang,Zhu, Dianhu,Qiu, Zihang,Li, Jianbin,Li, Chao-Jun
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p. 9199 - 9205
(2019/10/14)
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- Solvent-free ring cleavage hydrazinolysis of certain biginelli pyrimidines
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Certain Biginelli pyrimidines with ester substitution in C5 were subjected to unexpected ring opening upon solvent-free reaction with hydrazine hydrate to give three products: pyrazole, arylidenehydrazines, and urea/thiourea, respectively. The nonisolable carbohydrazide intermediates are formed firstly followed by the intermolecular nucleophilic attack of terminal amino group of hydrazide function on sp2 C6 rather than the sp3 C4 to give the ring adduct which was produced as a final product.
- Said, Mohamed A.,Eldehna, Wagdy M.,Ghabbour, Hazem A.,Kabil, Maha M.,Al-shakliah, Nasser S,Abdel-Aziz, Hatem A
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- Mechanistic Studies on the Michael Addition of Amines and Hydrazines to Nitrostyrenes: Nitroalkane Elimination via a Retro-aza-Henry-Type Process
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In this article we report on the mechanistic studies of the Michael addition of amines and hydrazines to nitrostyrenes. Under the present conditions, the corresponding N-alkyl/aryl substituted benzyl imines and N-methyl/phenyl substituted benzyl hydrazones were observed via a retro-aza-Henry-type process. By combining organic synthesis and characterization experiments with computational chemistry calculations, we reveal that this reaction proceeds via a protic solvent-mediated mechanism. Experiments in deuterated methanol CD3OD reveal the synthesis and isolation of the corresponding deuterated intermediated Michael adduct, results that support the proposed slovent-mediated pathway. From the synthetic point of view, the reaction occurs under mild, noncatalytic conditions and can be used as a useful platform to yield the biologically important N-methyl pyrazoles in a one-pot manner, simple starting with the corresponding nitrostyrenes and the methylhydrazine.
- Kallitsakis, Michael G.,Tancini, Peter D.,Dixit, Mudit,Mpourmpakis, Giannis,Lykakis, Ioannis N.
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p. 1176 - 1184
(2018/02/09)
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- Rational modifications on a benzylidene-acrylohydrazide antiviral scaffold, synthesis and evaluation of bioactivity against Chikungunya virus
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Chikungunya virus is a re-emerging arbovirus transmitted to humans by Aedes mosquitoes, responsible for an acute febrile illness associated with painful and debilitating arthralgia, which can persist for several months or become chronic. Over the past few years, infection with this virus has spread worldwide with a previously unknown virulence. No specific antiviral treatments nor vaccines are currently available against this important pathogen. Starting from the structure of a class of selective anti-CHIKV agents previously identified in our research group, different modifications to this scaffold were rationally designed, and 69 novel small-molecule derivatives were synthesised and evaluated for their inhibition of Chikungunya virus replication in Vero cells. Further structure-activity relationships associated with this class of antiviral agents were elucidated for the original scaffolds, and novel antiviral compounds with EC50 values in the low micromolar range were identified. This work provides the foundation for further investigation of these new structures as antivirals against Chikungunya virus.
- Giancotti, Gilda,Cancellieri, Michela,Balboni, Andrea,Giustiniano, Mariateresa,Novellino, Ettore,Delang, Leen,Neyts, Johan,Leyssen, Pieter,Brancale, Andrea,Bassetto, Marcella
-
supporting information
p. 56 - 68
(2018/03/06)
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- Structure-Guided Synthesis and Mechanistic Studies Reveal Sweetspots on Naphthyl Salicyl Hydrazone Scaffold as Non-Nucleosidic Competitive, Reversible Inhibitors of Human Ribonucleotide Reductase
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Ribonucleotide reductase (RR), an established cancer target, is usually inhibited by antimetabolites, which display multiple cross-reactive effects. Recently, we discovered a naphthyl salicyl acyl hydrazone-based inhibitor (NSAH or E-3a) of human RR (hRR) binding at the catalytic site (C-site) and inhibiting hRR reversibly. We herein report the synthesis and biochemical characterization of 25 distinct analogs. We designed each analog through docking to the C-site of hRR based on our 2.7 ? X-ray crystal structure (PDB ID: 5TUS). Broad tolerance to minor structural variations preserving inhibitory potency is observed. E-3f (82% yield) displayed an in vitro IC50 of 5.3 ± 1.8 μM against hRR, making it the most potent in this series. Kinetic assays reveal that E-3a, E-3c, E-3t, and E-3w bind and inhibit hRR through a reversible and competitive mode. Target selectivity toward the R1 subunit of hRR is established, providing a novel way of inhibition of this crucial enzyme.
- Huff, Sarah E.,Mohammed, Faiz Ahmad,Yang, Mu,Agrawal, Prashansa,Pink, John,Harris, Michael E.,Dealwis, Chris G.,Viswanathan, Rajesh
-
supporting information
p. 666 - 680
(2018/02/16)
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- Nickel-catalyzed cross-coupling of aldehydes with aryl halides: Via hydrazone intermediates
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Traditional cross-couplings require stoichiometric organometallic reagents. A novel nickel-catalyzed cross-coupling reaction between aldehydes and aryl halides via hydrazone intermediates has been developed, merging the Wolff-Kishner reduction and the classical cross-coupling reactions. Aromatic aldehydes, aryl iodides and aryl bromides are especially effective in this new cross-coupling chemistry.
- Tang, Jianting,Lv, Leiyang,Dai, Xi-Jie,Li, Chen-Chen,Li, Lu,Li, Chao-Jun
-
supporting information
p. 1750 - 1753
(2018/02/21)
-
- Cross-Coupling of Phenol Derivatives with Umpolung Aldehydes Catalyzed by Nickel
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A nickel-catalyzed cross-coupling to construct the C(sp2)-C(sp3) bond was developed from two sustainable biomass-based feedstocks: phenol derivatives with umpolung aldehydes. This strategy features the in situ generation of moisture/air-stable hydrazones from naturally abundant aldehydes, which act as alkyl nucleophiles under catalysis to couple with readily available phenol derivatives. The avoidance of using both halides as the electrophiles and organometallic or organoboron reagents (also derived from halides) as the nucleophiles makes this method more sustainable. Water tolerance, great functional group (ketone, ester, free amine, amide, etc.) compatibility, and late-stage elaboration of complex biological molecules exemplified its practicability and unique chemoselectivity over organometallic reagents.
- Lv, Leiyang,Zhu, Dianhu,Tang, Jianting,Qiu, Zihang,Li, Chen-Chen,Gao, Jian,Li, Chao-Jun
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p. 4622 - 4627
(2018/05/22)
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- Umpolung of Carbonyl Groups as Alkyl Organometallic Reagent Surrogates for Palladium-Catalyzed Allylic Alkylation
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Palladium-catalyzed allylic alkylation of nonstabilized carbon nucleophiles is difficult and remains a major challenge. Reported here is a highly chemo- and regioselective direct palladium-catalyzed C-allylation of hydrazones, generated from carbonyls, as a source of umpolung unstabilized alkyl carbanions and surrogates of alkyl organometallic reagents. Contrary to classical allylation techniques, this umpolung reaction utilizes hydrazones prepared not only from aryl aldehydes but also from alkyl aldehydes and ketones as renewable feedstocks. This strategy complements the palladium-catalyzed coupling of unstabilized nucleophiles with allylic electrophiles by providing an efficient and selective catalytic alternative to the traditional use of highly reactive alkyl organometallic reagents.
- Zhu, Dianhu,Lv, Leiyang,Li, Chen-Chen,Ung, Sosthene,Gao, Jian,Li, Chao-Jun
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supporting information
p. 16520 - 16524
(2018/11/23)
-
- Carbonyls as Latent Alkyl Carbanions for Conjugate Additions
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Conjugate addition of carbon nucleophiles to electron-deficient olefins is one of the most powerful methods for forming carbon–carbon bonds. Despite great achievements in controlling the selectivity, variation of the carbon nucleophiles remains largely underexplored, with this approach relying mostly on organometallic reagents. Herein, we report that naturally abundant carbonyls can act as latent carbon nucleophiles for conjugate additions through a ruthenium-catalyzed process, with water and nitrogen as innocuous byproducts. The key to our success is homogeneous ruthenium(II) catalysis, combined with phosphines as spectator ligands and hydrazine as the reducing agent. This chemistry allows the incorporation of highly functionalized alkyl fragments into a vast array of electron-deficient olefins under mild reaction conditions in a reaction complementary to the classical organometallic-reagent-based conjugate additions mediated or catalyzed by “soft” transition metals.
- Dai, Xi-Jie,Wang, Haining,Li, Chao-Jun
-
supporting information
p. 6302 - 6306
(2017/05/19)
-
- Umpolung Addition of Aldehydes to Aryl Imines
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One of the classical ways to synthesize amines involves the coupling of carbonyl compounds and imines, either through enolate chemistry or acyl-based carbanion equivalents. We herein report an alternative strategy that is based on the use of aldehydes as alkyl carbanion equivalents in a reductive coupling with aryl imines. A wide array of secondary amines can be synthesized in moderate to high yields. This reaction is mediated by hydrazine and catalyzed by ruthenium(II) complexes, and it tolerates various functional groups, such as esters, amides, and nitriles.
- Chen, Ning,Dai, Xi-Jie,Wang, Haining,Li, Chao-Jun
-
supporting information
p. 6260 - 6263
(2017/05/19)
-
- Synthesis of Aryldihalomethanes by Denitrogenative Dihalogenation of Benzaldehyde Hydrazones
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We report a denitrogenative dihalogenation reaction of phenyldiazomethanes in which the hypervalent iodine reagents PhICl2 and TolIF2 act as surrogates for elemental chlorine and fluorine. Halogen transfer from iodane to aryldiazomethane is described, as is a tandem oxidative dihalogenation reaction between iodane and hydrazone. This is the first use of non-α-stabilized diazo compounds in this reaction, which provided an efficient synthesis of aryldifluoromethane (ArCHF2) and aryldichloromethane (ArCHCl2) derivatives. (Figure presented.).
- Zhao, Zhensheng,Kulkarni, Kaivalya G.,Murphy, Graham K.
-
supporting information
p. 2222 - 2228
(2017/07/07)
-
- A novel one pot multi-component strategy for facile synthesis of 5-aryl-[1,2,4]triazolidine-3-thiones
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We have disclosed an efficient, one pot, novel multi-component approach for the synthesis of 5-aryl-[1,2,4]triazolidine-3-thiones from aldehyde, hydrazine hydrate, and trimethylsilyl isothiocyanate (TMSNCS) in the presence of catalytic amount of sulfamic acid. High yields, easy work-up procedure, no chromatographic separation, and novelty in multi-component strategy are the main merits of the present strategy.
- Mane,Pore
-
supporting information
p. 6601 - 6604
(2015/01/09)
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- A simple one-pot procedure for the synthesis of 1,2,4-triazolo[1,5-a ]pyrid-ines via pseudo five-component reactions catalyzed by molecular iodine
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In this paper we report the synthesis of the 1,2,4-triazolo[1,5-a]pyridine ring system. The reaction between benzylidenehydrazines, dialkyl acetylenedicarboxylates, benzaldehydes, and malononitrile proceeds in EtOH at reflux in the presence of molecular iodine as catalyst in good to excellent yields. Georg Thieme Verlag Stuttgart · New York.
- Alizadeh, Abdolali,Saberi, Vahid,Mokhtari, Javad
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p. 1825 - 1829
(2013/09/12)
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- Synthesis of 2-aryl-5-oxo-4-[2-(phenylmethylidene)hydrazino]-2,5-dihydro- 1H-pyrrole-3-carboxylates by the reaction between hydrazones, acetylenedicarboxylates, and 1-aryl-N,N′-bis(arylmethylidene) methanediamines
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An efficient approach for the preparation of functionalized 2-aryl-2,5-dihydro-5-oxo-4-[2-(phenylmethylidene)hydrazino]-1H-pyrroles is described. The four-component reaction between aldehydes, NH2NH 2×H2O, dialkyl acetylenedicarboxylates, and 1-aryl-N,N′-bis(arylmethylidene)methanediamines proceeds in EtOH under reflux in good-to-excellent yields (Scheme 1). The structures of 4 were corroborated spectroscopically (IR, 1H- and 13C-NMR, and EI-MS, and, in the case of 4f, by X-ray crystallography). A plausible mechanism for this type of reaction is proposed (Scheme 2). Copyright
- Alizadeh, Abdolali,Saberi, Vahid,Mokhtari, Javad
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p. 1991 - 1996
(2013/11/06)
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- Facile method for the conversion of semicarbazones/thiosemicarbazones into azines (Under Microwave Irradiation) and oxadiazoles (By Grinding)
-
In an effective transformation, semicarbazones/thiosemicarbazones are smoothly converted into azines under microwave irradition. Oxadiazoles are also obtained from semicarbazones by reaction with bromine generated in situ via a grinding reaction in the solid phase. Taylor &Francis Group, LLC.
- Chattopadhyay, Gautam,Ray, Partha Sinha
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experimental part
p. 2607 - 2614
(2011/08/07)
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- An enantioselective synthesis of 2-aryl cycloalkanones by sc-catalyzed carbon insertion
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Current methods for asymmetric α-arylation require blocking groups to prevent reaction at the R0-carbon, basic conditions that promote racemization, or multistep synthesis. This work records the first catalytic enantioselective examples of the diazoalkane-carbonyl homologation reaction. Medium ring 2-aryl ketones are prepared in one step in up to 98:2 er and 99% yield from the unsubstituted lower homologue by Sc-catalyzed aryldiazomethyl insertion with simple bis- and tris(oxazoline) ligands.
- Rendina, Victor L.,Moebius, David C.,Kingsbury, Jason S.
-
supporting information; experimental part
p. 2004 - 2007
(2011/07/07)
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- Novel efficient synthesis of β-fluoro-β-(trifluoromethyl)styrenes
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CF3CFBr2 was employed in catalytic olefination reactions of aromatic aldehydes. In situ prepared hydrazones of aldehydes were transformed to β-fluoro-β-(trifluoromethyl)styrenes by reaction with CF3CFBr2 under CuCl catalysis. Based on this reaction, a novel stereoselective approach towards β-fluoro-β-(trifluoromethyl)styrenes was elaborated. Nucleophilic vinylic substitution of fluorine by secondary amines, thiolates and alkoxides in β-fluoro-β-(trifluoromethyl)styrenes was also tested.
- Goldberg, Aleksey A.,Muzalevskiy, Vasiliy M.,Shastin, Aleksey V.,Balenkova, Elisabeth S.,Nenajdenko, Valentine G.
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experimental part
p. 384 - 388
(2010/04/24)
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- Synthesis and Diels-Alder reactions of α-fluoro- and α-trifluoromethylacrylonitriles
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A novel synthetic method for the preparation of α-fluoro- and the still unknown α-trifluoromethylacrylonitriles is elaborated. The reaction of α-fluorovinylbromides and α-trifluoromethylvinylbromides with CuCN leads to the title compounds in good to high yields. While the α-fluoroacrylonitriles were isolated as mixture of Z/E-isomers, the α-trifluoromethylacrylonitriles were obtained as pure Z-isomers. The α-trifluoromethylacrylonitriles are shown to be excellent dienophiles for Diels-Alder reactions.
- Nenajdenko, Valentine G.,Muzalevskiy, Vasiliy M.,Shastin, Aleksey V.,Balenkova, Elizabeth S.,Haufe, Günter
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p. 818 - 826
(2008/03/14)
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- A convergent kilogram-scale synthesis of the PPARα Agonist LY518674: Discovery of a novel acid-mediated triazolone synthesis
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The first kilogram-scale synthesis of the PPARα agonist LY518674 (1) is described. The de novo convergent synthetic approach involved coupling of two rapidly assembled components, triazolone formation via a novel acid-promoted cyclization reaction, and final step saponification, delivering the compound in 32.5% overall yield via eight total steps with a six-step longest linear sequence. A regioselective alkylation on the dianion of 4-hydroxyphenylbutyric acid allowed the direct preparation of one of the convergent coupling partners, carboxylic acid 12, and an unusual solvent effect enabled the installation of a urea group on a protected hydrazine, permitting the regiospecific preparation of the other coupling partner, semicarbazide mesylate 17. Sulfonic acids were found to effect the desired triazolone ring formation, affording 25 from the coupled precursor acyl semicarbazide 23. Following saponification of 25 to 1, a wide solubility differential between ethyl acetate extracts of 1 and solutions of 1 in anhydrous ethyl acetate was harnessed in the final crystallization step to deliver the final compound in high yield and purity. The novel acid-mediated triazolone formation was further evaluated on a range of additional substrates, showing the new methodology to be largely complementary to existing base-mediated triazolone syntheses.
- Braden, Timothy M.,Coffey, D. Scott,Doecke, Christopher W.,LeTourneau, Michael E.,Martinelli, Michael J.,Meyer, Christopher L.,Miller, Richard D.,Pawlak, Joseph M.,Pedersen, Steven W.,Schmid, Christopher R.,Shaw, Bruce W.,Staszak, Michael A.,Vicenzi, Jeffrey T.
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p. 431 - 440
(2012/12/31)
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- A new synthetic approach to α-chlorocinnamaldehydes
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A new simple and efficient transformation of aromatic aldehydes into α-chlorocinnamaldehydes is described. Catalytic olefination reaction of hydrazones of aromatic aldehydes with 2-trichloromethyl-1,3-dioxolane gives ethylene acetals of target alkenes in moderate to good yields. The reaction proceeds stereoselectively to form preferably Z-isomers.
- Nenajdenko, Valentine G.,Reznichenko, Alexander L.,Lenkova, Olesya N.,Shastin, Alexey V.,Balenkova, Elizabeth S.
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p. 605 - 609
(2007/10/03)
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- The catalytic olefination reaction of aldehydes and ketones with CBr 3CF3
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The new approach of catalytic olefination reaction (COR) has been used to convert aromatic and aliphatic aldehydes and ketones to 2-bromo-3,3,3- trifluoroprop-1-enes by the treatment of corresponding hydrazones with CBr 3CF3 under copper(I) catalysis conditions. The reaction proceeds stereoselectively, the target alkenes were obtained in good yields.
- Nenajdenko, Valentine G.,Varseev, Georgy N.,Shastin, Alexey V.,Balenkova, Elisabeth S.
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p. 907 - 913
(2007/10/03)
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- Reaction of CBrF2-CBrF2 with hydrazones of aromatic aldehydes. Novel efficient synthesis of fluorocontaining alkanes, alkenes and alkynes
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An olefination of hydrazones of aromatic aldehydes by CBrF2-CBrF2 under copper catalysis was investigated. In situ prepared aldehydes hydrazones were converted to (3-bromo-2,2,3,3-tetrafluoropropyl)arenes by reaction with CBrF2-CBrF2 in the presence of CuCl. Subsequent elimination of HF by sodium hydroxide resulted in stereospecific formation of fluorocontaining alkenes. Elimination proceeds stereoselectively, only Z -isomers of alkenes are formed. Elimination of two molecules of HF from (3-bromo-2,2,3,3-tetrafluoropropyl)arenes by treatment with potassium tert -butoxide leads to formation of (bromodifluoromethyl)alkynes. As a result a simple and efficient transformation of aromatic aldehydes to range of various fluorinated alkanes, alkenes and alkynes was elaborated.
- Nenajdenko, Valentine G.,Varseev, Georgy N.,Korotchenko, Vasily N.,Shastin, Alexey V.,Balenkova, Elisabeth S.
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p. 1339 - 1345
(2007/10/03)
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- New synthetic approach to α-chlorocinnamates: First example of synthesis of functionally substituted alkenes using catalytic olefination reaction
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A new simple and efficient transformation of carbonyl compounds to α-chlorocinnamates is described. Catalytic olefination reaction with ethyl trichloroacetate gives target alkenes in moderate to good yields. The reaction with aromatic aldehydes proceeds stereoselectively to form preferably Z-isomers.
- Nenajdenko, Valentine G.,Lenkova, Olesya N.,Shastin, Alexey V.,Balenkova, Elizabeth S.
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p. 573 - 577
(2007/10/03)
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- A novel direct synthesis of (2,2-difluorovinyl)benzenes from aromatic aldehydes
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A novel catalytic approach to (2,2-difluorovinyl)benzenes has been developed. It was found that hydrazones of aromatic aldehydes generated in situ could be converted to the corresponding (2,2-difluorovinyl)benzenes by catalytic olefination reaction (COR) with dibromodifluoromethane in the presence of CuCl.
- Nenajdenko, Valentine G.,Varseev, Georgy N.,Korotchenko, Vasily N.,Shastin, Alexey V.,Balenkova, Elisabeth S.
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p. 115 - 118
(2007/10/03)
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- A novel approach to fluoro-containing alkenes
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A new and general one-pot transformation of aromatic aldehydes to fluorinated olefins containing -CH=C(Cl)CF3 or -CH=C(F)CClF2 moieties is described. Freons CCl3CF3 and CCl2FCClF2 were used as trifluoromethyl and difluoromethyl C2-building blocks respectively. A proposed mechanism for the reaction is discussed.
- Korotchenko, Vasily N,Shastin, Alexey V,Nenajdenko, Valentine G,Balenkova, Elisabeth S
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p. 7519 - 7527
(2007/10/03)
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- Pyrolysis of amino nitriles, cyanohydrazones, and cyanoacetamides. Part I. Elimination reaction of 1-arylmethyleneamino-1,2-dihydro-4, 6-dimethyl-2-oxopyridine-3-carbonitriles and substituted benzaldehyde cyanoacetylhydrazones
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Pyrolysis of the Schiff bases of 1-arylmethyleneamino-1,2-dihydro-4, 6-dimethyl-2-oxopyridine-3-carbonitriles (1-5) has been studied. These compounds eliminate via a six-membered transition state to produce substituted benzonitriles and 2-hydroxy-4,6-dimethylpyridine-3-carbonitrile. These eliminations are unimolecular first-order reactions. The kinetic data gave a good correlation with σ0 values of the substituents on the aryl group with ρ = 0.83 at 520 K. Utilization of the pyrolytic reaction in synthesis of various benzonitriles is considered, and mechanistic information has been obtained by comparing the kinetic data and product analysis of the Schiff bases with their open-chain substituted benzaldehyde cyanoacetylhydrazones (6-9) analogues.
- Al-Awadi,Elnagdi,Mathew,El-Gamry,Abdel Khalik
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p. 741 - 748
(2007/10/03)
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- Diazoalkane Complexes of Molybdenum and Tungsten
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Ordinary diazoalkanes, N2CHR' and N2C(CH3)R' (R' = C6H5, p-CH3C6H4), were found to react with M(CO)3(S2CNR2)2 (M = Mo, W; R = CH3, C2H5; R2 = (CH2)4) at room temperature to form stable complexes of the type M(CO)(N2CHR')(S2CNR2)2 which were conveniently isolated in good yields.Oxidaion of M(CO)(N2CHR')(S2CNR2)2 with 1 equiv of Cl2 or Br2 produced MX2(N2CHR')(S2CNR2)2 (X = Cl, Br) which were isolated as chloroform solvates.The addition of excess HBr to W(CO)(N2CHR')(S2CNMe2)2 gave a red solid which analyzed for WBr2(N2H2CHR')(S2CNMe2)2.Physical and spectroscopic data suggest that the diazoalkane ligands in the above complexes behave as terminal, singly bent, four-electron donor ligands.The NMR chemical shifts of the methine proton in N2CHR' ligands indicate that the M(S2CNR2)2 unit is strogly electron withdrawing.Syntheses for new tungsten compounds, W(CO)3(S2CNR2)2, W(CO)2(S2CNR2)2, W(CO)2(L)(S2CNR2)2 (L = p-CH3C6H4NHNH2, 4-CH3C5H4N), WBr2(S2CNR2)2, W(S2CNR2)4, and WBr3(S2CNR2)2, are also reported.
- Hillhouse, Gregory L.,Haymore, Barry L.
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p. 1537 - 1548
(2007/10/02)
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