- Solvent free, light induced 1,2-bromine shift reaction of α-bromo ketones
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Photolysis of α-bromopropiophenones in acetonitrile results in formation of β-bromopropiophenones with good product selectivity, which can be coined as 1,2-Br shift reaction. The product selectivity increases when the reaction is done in neat or solid state, where only the 1,2-Br shift product is formed in some cases. The reaction is suggested to proceed by C–Br bond homolysis to give a radical pair, followed by disproportionation and conjugate addition of HBr to the α,β-unsaturated ketone intermediate. When the unsaturated intermediate is stabilized by an extra conjugation, the reaction stops at the stage, in which the unsaturated ketone becomes a major product. The synthetic method described in this research fits in a category of eco-friendly organic synthesis nicely since the reaction does not use volatile organic solvents and any other additives such as acid, base or metal catalysts, etc. Besides, the method fits into perfect atom economy, which does not give any side products. The synthetic method should find much advantage over other alternative methods to obtain β-bromo carbonyl compounds.
- An, Sejin,Moon, Da Yoon,Park, Bong Ser
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p. 6922 - 6928
(2018/10/24)
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- Fe-Catalyzed Cycloisomerization of Aryl Allenyl Ketones: Access to 3-Arylidene-indan-1-ones
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A cycloisomerization of aryl allenyl ketones to 3-arylidene-indan-1-ones using a cationic Fe-complex as a catalyst is reported. The catalyst opens a synthetically interesting reaction pathway to this surprisingly underrepresented class of indanones that are not accessible using alternative catalytic systems.
- Teske, Johannes,Plietker, Bernd
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p. 2257 - 2260
(2018/04/27)
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- Acidity versus metal-induced Lewis acidity in zeolites for Friedel–Crafts acylation
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Acid catalysts including Ni, Ag and Fe-loaded zeolites of different structures were prepared either via cationic exchange or impregnation techniques from pristine H-zeolites (BEA, and MFI). Their catalytic activity was evaluated in the liquid-phase Friedel–Crafts acylation of anisole with propanoic acid. It turned out that, whatever the doping procedure was, the zeolite loaded with transition metals led to considerable decrease in propanoic acid conversion, regardless of the nature or the metal content. However, the extent of this detrimental effect followed the order: Ag+?>?Ni2+?>?Fe3+. Pristine acidic zeolites were not only found to be the most active, but also to be the most selective toward ortho- and para-acylation products. H-ZSM-5 zeolites yielded the highest intrinsic activity, with TOF values of 0.09?h?1. The catalyst activity proved to be essentially attributed to the density and accessibility of Br?nsted acid sites, playing a key role in the activation of the reactants. Br?nsted sites are proposed to be the most likely catalytic species for performing this Friedel–Crafts acylation.
- Bernardon, Claire,Ben Osman, Manel,Laugel, Guillaume,Louis, Beno?t,Pale, Patrick
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- An efficient and green method for regio- and chemo-selective Friedel-Crafts acylations using a deep eutectic solvent ([CholineCl][ZnCl2]3)
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[CholineCl][ZnCl2]3, a deep eutectic solvent between choline chloride and ZnCl2, has been used as a dual function catalyst and green solvent for the Friedel-Crafts acylation of aromatic compounds instead of using the moisture-sensitive Lewis acids and volatile organic solvents. The reactions are performed with high yields under microwave irradiation with short reaction times for the synthesis of ketones. Interestingly, indole derivatives are regioselectively acylated in the 3-position under mild conditions with high yields without NH protection. Three new ketone products are synthesized. [CholineCl][ZnCl2]3 is easily synthesized from choline chloride and zinc chloride at a low cost, with easy purification and environmentally benign compounds. [CholineCl][ZnCl2]3 can be reused up to five times without loss of catalytic activity, making it ideal in industrial processes.
- Tran, Phuong Hoang,Nguyen, Hai Truong,Hansen, Poul Erik,Le, Thach Ngoc
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p. 37031 - 37038
(2016/05/24)
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- DMF as carbon source: Rh-catalyzed α-methylation of ketones
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An unprecedented Rh-catalyzed direct methylation of ketones with N,N-dimethylformamide (DMF) is disclosed. The reaction shows a broad substrate scope, tolerating both aryl and alkyl ketones with various substituents. Mechanistic studies suggest that DMF delivers a methylene fragment followed by a hydride in the methylation process.
- Li, Yang,Xue, Dong,Lu, Wei,Wang, Chao,Liu, Zhao-Tie,Xiao, Jianliang
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supporting information
p. 66 - 69
(2014/01/23)
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- Advancing the mechanistic understanding of an enantioselective palladium-catalyzed alkene difunctionalization reaction
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The mechanism of an enantioselective palladium-catalyzed alkene difunctionalization reaction has been investigated. Kinetic analysis provides evidence of turnover-limiting attack of a proposed quinone methide intermediate with MeOH and suggests that copper is involved in productive product formation, not just catalyst turnover. Through examination of substrate electronic effects, a Jaffe relationship was observed correlating rate to electronic perturbation at two positions of the substrate. Ligand effects were evaluated to provide evidence of rapid ligand exchange between palladium and copper as well as a correlation between ligand electronic nature and enantioselectivity.
- Jensen, Katrina H.,Webb, Jonathan D.,Sigman, Matthew S.
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scheme or table
p. 17471 - 17482
(2011/02/27)
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- PYRIDAZINONE COMPOUNDS AS CALCILYTICS
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Various calcilytic compounds and pharmaceutical compositions containing these compounds are disclosed. Calcilytic compounds are compounds capable of inhibiting calcium receptor activity. Methods for preparing calcilytic compounds, oral bioavailability of calcilytic compounds, and their use as calcium receptor antagonists are also disclosed.
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Page/Page column 31
(2010/11/27)
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- Palladium(II)-catalyzed aerobic dialkoxylation of styrenes: A profound influence of an o-phenol
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We report a Pd(II)-catalyzed aerobic dialkoxylation of styrene derivatives that requires an o-phenol. Initial scope and preliminary mechanistic studies are presented in which the o-phenol is proposed to facilitate the formation of a quinone methide intermediate. Copyright
- Schultz, Mitchell J.,Sigman, Matthew S.
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p. 1460 - 1461
(2007/10/03)
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- COMPOUNDS, METHODS AND FORMULATIONS FOR THE ORAL DELIVERY OF A GLUCAGON LIKE PEPTIDE (GLP)-1 COMPOUND OR AN MELANOCORTIN 4 RECEPTOR (MC4) AGONIST PEPTIDE
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The present invention relates to novel compounds, methods, and formulations useful for the oral delivery of a GLP-1 compound or an MC4 agonist peptide.
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Page/Page column 76
(2008/06/13)
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- Chloroindate(III) ionic liquids: Recyclable media for Friedel-Crafts acylation reactions
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Chloroindate(III) ionic liquids are versatile reaction media for Friedel-Crafts acylation reactions; the system is catalytic and totally recyclable, using an aqueous workup, with no leaching of the indium into the product phase. The Royal Society of Chemistry 2005.
- Earle, Martyn J.,Hakala, Ullastiina,Hardacre, Christopher,Karkkainen, Johanna,McAuley, Barry J.,Rooney, David W.,Seddon, Kenneth R.,Thompson, Julian M.,Waehaelae, Kristina
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p. 903 - 905
(2007/10/03)
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- Aluminum dodecatungstophosphate (AlPW12O40) as a non-hygroscopic Lewis acid catalyst for the efficient Friedel-Crafts acylation of aromatic compounds under solvent-less conditions
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Stable and non-hygroscopic aluminum dodecatungstophosphate (AlPW 12O40), which is prepared easily from cheap and commercially available compounds was found to be an effective catalyst for Friedel-Crafts acylation reactions using carboxylic acids, acetic anhydride and benzoyl chloride in the absence of solvent under mild reaction conditions.
- Firouzabadi, Habib,Iranpoor, Nasser,Nowrouzi, Farhad
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p. 10843 - 10850
(2007/10/03)
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- Diminished reactivity of ortho-substituted phenacyl bromides toward nucleophilic displacement
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A systematic increase of substitution rates by tert-butylamine on α-bromopropiophenones is observed with meta or para substituents with increasing electron-withdrawing ability (k x 103 L M-1 min-1 = 12.7 (p-CH3), 15.7 (o-F), 20.5 (H), 20.0 (p-Cl), 23.6 (m-Cl), 27.3 (p-CF3)). Within an ortho-substituted series, the reactivities decrease (k x 103 L M-1 min-1 = 7.64 (o-OCH3), 5.31 (o-CH3), 2.85 (o-Cl), 2.40 (o-CF3)). Ortho-substitution results occur from rotational barrier effects and an Aδσ + Bδσ + repulsion. The major bonding contribution between reaction and α-substituent centers (A-B) is only the σ bond. When π bonding is allowed between A and B (meta/para-substitution), delocalization and stabilization of the reacting center occurs.
- Kalendra, Diane M.,Sickles, Barry R.
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p. 1594 - 1596
(2007/10/03)
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- Efficient acylation of toluene and anisole with aliphatic carboxylic acids catalysed by heteropoly salt Cs2.5H0.5PW12O40
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Heteropoly salt Cs2.5H0.5PW12O40 is a highly efficient and reusable solid acid catalyst for the liquid-phase acylation of toluene or anisole with C2 - C12 aliphatic carboxylic acids.
- Kaur, Jaspal,Kozhevnikov, Ivan V.
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p. 2508 - 2509
(2007/10/03)
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- Evidence that the availability of an allylic hydrogen governs the regioselectivity of the Wacker oxidation
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The allylic hydrogen is found to have a dramatic effect on the regioselectivity of the Wacker oxidation, leading to the postulation that an agostic hydrogen or enyl (σ + π) complex helps to stabilise the key intermediate.
- Gaunt,Yu,Spencer
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p. 1844 - 1845
(2007/10/03)
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- Compounds active at a novel site on receptor-operated calcium channels useful for treatment of neurological disorders and diseases
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Method and compositions for treating a patient having a neurological disease or disorder, such as stroke, head trauma, spinal cord injury, spinal cord ischemia, ischemia- or hypoxia-induced nerve cell damage, epilepsy, anxiety, neuropsychiatric or cogniti
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- Propionylation of anisole to 4-methoxypropiophenone over zeolite H-beta
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The results of a detailed study of the propionylation of anisole over various medium and large pore zeolites such as H-ZSM-5, H-beta, H-Na-beta, H- mordenite, H-Y and H-RE-Y are presented and discussed. In addition, homogenous catalysts and amorphous SiO2-Al2O3 are also included for comparison. The catalyst and process parameters are optimised to enhance the conversion of propionyl chloride(PC) and selectivity to 4- methoxypropiophenone(4-MOPP).
- Sugunan,Jacob, Bindhu,Jose, Binoy
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p. 1189 - 1193
(2007/10/03)
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- Stereoselective Reduction of γ-Oxobutanoic Acids Using DIBAL-H and ZnCl2
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A variety of γ-aromatic γ-ketobutanoic acids can be reduced selectively, under optimized conditions, by the use of DIBAL-H and ZnCl2 to provide the (RS,SR)-γ-aryl-γ-hydroxy-β-methylbutanoic acids.Further evidence has been gathered to support the hypothesis that the reaction proceeds by formation of a seven-membered ring complex with the aluminium or zinc atom bridging the ketone and carboxyl groups which preceeds the reduction step and that this templated reduction accounts for observed high diastereoselectivity.Also we have shown that some γ-aryl-γ-butyrolactones can be easily transformed via an oxidative cleavage of the aromatic ring to provide selective synthesis of either cis- or trans-tetrahydro-3-methyl-5-oxo-2-furancarboxylic acid derivatives.
- Frenette, R.,Monette, M.,Bernstein, M. A.,Young, R. N.,Verhoeven, T. R.
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p. 3083 - 3089
(2007/10/02)
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- The Synthesis of Indan-1-ones and Isocoumarins
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A flexible synthetic route leading via indan-1-ones to variously methylated and oxygenated isocoumarins is described.The indanones are prepared by alternative routes involving intramolecular Friedel-Crafts cyclisation of arylpropionic acids or pericyclic ring closure of acrylophenones.The influence of substitution on the rate of the pericyclic reaction is assessed.
- Carter, Rachel H.,Garson, Mary J.,Hill, Robert A.,Staunton, James,Sunter, David C.
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p. 471 - 479
(2007/10/02)
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