- 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
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p. 2870 - 2875
(2021/03/14)
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- Amino- and azidocarbonylation of iodoalkenes
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Iodoalkenes, available from ketones via their hydrazones, underwent palladium-catalysed azidocarbonylation. Depending on the structure of the acyl azides, consecutive hydrolysis toward corresponding primary amides was observed. ‘Direct’ aminocarbonylation
- Mikle, Gábor,Skoda-F?ldes, Rita,Kollár, László
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- Sequential Suzuki-Miyaura Coupling/Lewis Acid-Catalyzed Cyclization: An Entry to Functionalized Cycloalkane-Fused Naphthalenes
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Functionalized angular cycloalkane-fused naphthalenes were prepared using a two-step process involving a Pd-catalyzed Suzuki-Miyaura coupling of aryl pinacol boronates and vinyl triflates followed by a boron trifluoride etherate-catalyzed cycloaromatization.
- Mahecha-Mahecha, Camilo,Lecornué, Frédéric,Akinari, Sumita,Charote, Thomas,Gamba-Sánchez, Diego,Ohwada, Tomohiko,Thibaudeau, Sébastien
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supporting information
p. 6267 - 6271
(2020/09/02)
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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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supporting information
p. 5777 - 5782
(2018/05/14)
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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)
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- Synthesis of 2- and 2,3-substituted Pyrazolo[1,5- a ]pyridines: Scope and mechanistic considerations of a domino direct alkynylation and cyclization of n -iminopyridinium ylides using alkenyl bromides, alkenyl iodides, and alkynes
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Direct functionalization and tandem processes have both received considerable recent interest due to their cost and time efficiency. Herein we report the synthesis of difficult to obtain 2-substituted pyrazolo[1,5-a] pyridines through a tandem palladium-catalyzed/silver-mediated elimination/direct functionalization/cyclization reaction involving N-benzoyliminopyridinium ylides. As such, these biologically important molecules are prepared in an efficient, high-yielding manner, only requiring a two-step sequence from pyridine. Aryl-substituted alkenyl bromides and iodides are effective ylide coupling partners. Mechanistic studies led to the use of terminal alkynes, which extended the scope of the reaction to include alkyl substitution on the unsaturated reactive site. The optimization, scope, and mechanistic considerations of the process are discussed.
- Mousseau, James J.,Bull, James A.,Ladd, Carolyn L.,Fortier, Angelique,Sustac Roman, Daniela,Charette, Andre B.
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experimental part
p. 8243 - 8261
(2012/01/03)
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- Copper-catalyzed direct alkenylation of N-iminopyridinium ylides
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(Figure Presented) A versatile Cu-catalyzed direct C-H alkenylation of N-iminopyridinium ylides, compatible with several different copper sources (including a penny), provides a powerful and inexpensive method for the synthesis of functionalized pyridine derivatives. Chemoselective functionalization of halide-containing compounds allows the synthesis of alkenyl pyridines containing reactive tethers for further functionalization
- Mousseau, James J.,Bull, James A.,Charette, Andre B.
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supporting information; experimental part
p. 1115 - 1118
(2010/05/17)
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- Synthesis of highly substituted cyclobutane fused-ring systems from n-vinyl β-lactams through a one-pot domino process
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In this contribution, aminocyclobutanes, as well as eight-membered enamide rings, have been made from N-vinyl β-lactams. The eightmembered products have been formed by a [3,3]-sigmatropic rearrangement, whereas the aminocyclobutanes have been derived from a domino [3,3]-rearrangement/6π- electrocyclisation process. The aminocyclobutanes have been obtained in a highly diastereoselective fashion. The cyclobutane ring system tolerates fusion even if adjacent quaternary centres are present. Systems containing up to four fused rings are readily accessible. The reaction profile has been investigated by using Gaussian 03. This study suggests that two reaction pathways for aminocyclobutane formation are possible. In one pathway the [3,3]-sigmatropic rearrangement is the rate-limiting step and in the second pathway the electrocyclisation is rate limiting. Taken together, these reactions should facilitate the construction of fused heterocycles.
- Cheung, Lawrence L. W.,Yudin, Andrei K.
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supporting information; experimental part
p. 4100 - 4109
(2010/07/05)
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- Synthesis and photochemistry of 1-iodocyclohexene: Influence of ultrasound on ionic vs. radical behaviour
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Simultaneous application of UV light and ultrasonic irradiation to a reaction mixture containing 1-iodocyclohexene is reported. The irradiation of 1-iodocyclohexene in methanol was carried out with or without addition of zinc. The effect of ultrasound or mechanical stirring on this solid-liquid system was also compared. The irradiation of 1-iodocyclohexene in methanol in the presence of zinc increases the yield of the nucleophilic trapping product, compared with the yield after irradiation in the absence of zinc. The photodegradation of 1-iodocyclohexene was slightly accelerated after addition of zinc. A rapid formation of radical product was accompanied by substantial decrease of 1-iodocyclohexene after application of ultrasound and irradiation without the zinc. The ultrasound significantly affects the photobehaviour of this reaction, predominantly its radical route. The joint application of ultrasound and zinc contributes positively to the production of radical and ionic products. The sonochemical stirring is more effective than mechanical stirring.
- Blaskovicova, Marika,Gaplovsky, Anton,Blasko, Jaroslav
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p. 188 - 193
(2007/10/03)
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- Novel efficient synthesis of dibromoalkenes. A first example of catalytic olefination of aliphatic carbonyl compounds
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A new simple and efficient one pot transformation of various aliphatic carbonyl compounds to the corresponding dibromoalkenes is described. A wide range of hydrazones of aldehydes and ketones. prepared in situ, were easily converted into dibromoalkenes by treatment with carbon tetrabromide in the presence of CuCl. The reaction proceeds under mild conditions to give the target products in good to high yields.
- Korotchenko, Vasily N.,Shastin, Alexey V.,Nenajdenko, Valentine G.,Balenkova, Elizabeth S.
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p. 1906 - 1908
(2007/10/03)
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- Pyrazole urea-based inhibitors of p38 MAP kinase: From lead compound to clinical candidate
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We report on a series of N-pyrazole, N′-aryl ureas and their mode of binding to p38 mitogen activated protein kinase. Importantly, a key binding domain that is distinct from the adenosine 5′-triphoshate (ATP) binding site is exposed when the conserved activation loop, consisting in part of Asp168-Phe169-Gly170, adopts a conformation permitting lipophilic and hydrogen bonding interactions between this class of inhibitors and the protein. We describe the correlation of the structure-activity relationships and crystallographic structures of these inhibitors with p38. In addition, we incorporated another binding pharmacophore that forms a hydrogen bond at the ATP binding site. This modification affords significant improvements in binding, cellular, and in vivo potencies resulting in the selection of 45 (BIRB 796) as a clinical candidate for the treatment of inflammatory diseases.
- Regan, John,Moss, Neil,Pargellis, Chris,Pav, Sue,Proto, Alfred,Swinamer, Alan,Tong, Liang,Torcellini, Carol,Breitfelder, Steffen,Cirillo, Pier,Gilmore, Thomas,Graham, Anne G.,Hickey, Eugene,Klaus, Bernhard,Madwed, Jeffrey,Moriak, Monica
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p. 2994 - 3008
(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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- STUDIES ON THE OXIDATION OF HYDRAZONES WITH IODINE AND WITH PHENYLSELENENYL BROMIDE IN THE PRESENCE OF STRONG ORGANIC BASES; AN IMPROVED PROCEDURE FOR THE SYNTHESIS OF VINYL IODIDES AND PHENYL-VINYL SELENIDES
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The oxidation of hydrazones by iodine in the presence of strong organic bases (guanidines) has been studied.Improved yields of vinyl iodides can be obtained by inverse addition using dry solvents and with a final heating period where appropriate.The reaction has been extended to various dihydrazones with interesting results.In complementary studies hydrazones have been oxidized by phenylselenyl bromide in the presence of strong organic bases to give the corresponding phenyl vinyl selenides in good yield.
- Barton, Derek H. R.,Bashiardes, George,Fourrey, Jan-Louis
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p. 147 - 162
(2007/10/02)
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