1855-08-9Relevant articles and documents
Direct Umpolung Morita–Baylis–Hillman like α-Functionalization of Enones via Enolonium Species
Arava, Shlomy,Kapanaiah, Raja,Pathe, Gulab K.,Santra, Sourav K.,Szpilman, Alex M.
, p. 15171 - 15175 (2020/07/04)
Herein we report on the umpolung of Morita–Baylis–Hillman type intermediates and application to the α-functionalization of enone C?H bonds. This reaction gives direct access to α-chloro-enones, 1,2-diketones and α-tosyloxy-enones. The latter are important intermediates for cross-coupling reaction and, to the best of our knowledge, cannot be made in a single step from enones in any other way. The proposed mechanism is supported by spectroscopic studies. The key initial step involves conjugate attack of an amine (DABCO or pyridine), likely assisted by hypervalent iodine acting as a Lewis acid leading to formation of an electrophilic β-ammonium-enolonium species. Nucleophilic attack by acetate, tosylate, or chloride anion is followed by base induced elimination of the ammonium species to give the noted products. Hydrolysis of α-acetoxy-enones lead to formation of 1,2-diketones. The α-tosyl-enones participate in Negishi coupling reactions under standard conditions.
Palladium-Catalyzed Synthesis of 1,2-Diketones from Aryl Halides and Organoaluminum Reagents Using tert-Butyl Isocyanide as the CO Source
Chen, Bo,Wu, Xiao-Feng
supporting information, p. 636 - 641 (2020/01/31)
In this work, an interesting and practical procedure for the synthesis of 1,2-diketones from aryl halides and organoaluminum reagents has been developed. Employing tert-butyl isocyanide as the CO source and palladium as the catalyst, the desired 1,2-diketones were isolated in good to excellent yields with good functional group tolerance. Concerning the reaction partners, besides aryl halides, both alkyl- A nd arylaluminum reagents were all suitable substrates here.
Iron-catalyzed aerobic oxidative cleavage of the C-C σ-bond using air as the oxidant: Chemoselective synthesis of carbon chain-shortened aldehydes, ketones and 1,2-dicarbonyl compounds
Xing, Qi,Lv, Hui,Xia, Chungu,Li, Fuwei
, p. 489 - 492 (2016/01/12)
A simple iron-catalyzed aerobic oxidative C-C σ-bond cleavage of ketones has been developed. Readily available and environmentally benign air is used as the oxidant. This reaction avoids the use of noble metal catalysts or specialized oxidants, chemoselectively yielding carbon chain-shortened aldehydes, ketones and 1,2-dicarbonyl compounds without overoxidation.
New push–pull chromophores. Synthesis of 2-[4-Aryl-3-cyano-5-hydroxy-5-methyl-1H-pyrrol-2(5H)-ylidene]malononitriles
Fedoseev,Belikov, M. Yu.,Ershov,Bardasov,Tafeenko
, p. 1440 - 1443 (2016/11/29)
2-Aminoprop-1-ene-1,1,3-tricarbonitrile (malononitrile dimer) reacted with 1-arylpropane-1,2-diones in ethanol in the presence of piperidine to give new donor–acceptor chromophores, 2-[4-aryl-3-cyano-5-hydroxy-5-methyl-1H-pyrrole-2(5H)-ylidene]malononitriles.
A Desulfonylative Approach in Oxidative Gold Catalysis: Regiospecific Access to Donor-Substituted Acyl Gold Carbenes
Chen, Hongyi,Zhang, Liming
, p. 11775 - 11779 (2015/10/05)
Donor-substituted acyl gold carbenes are challenging to access selectively by gold-promoted intermolecular oxidation of internal alkynes as the opposite regioisomers frequently predominate. By using alkynyl sulfones or sulfonates as substrates, the oxidative gold catalysis in the presence of substituted pyridine N-oxides offers regiospecific access to acyl/aryl, acyl/alkenyl, and acyl/alkoxy gold carbenes by in situ expulsion of sulfur dioxide. The intermediacies of these reactive species are established by their reactivities, including undergoing further oxidation by the same oxidant, cyclopropanation of styrenes, engaging in a [3+2] cycloaddition with α-methylstyrene, and conversion into dienones. Accept it: A desulfonylative approach was developed to regiospecifically access these underexplored acyl gold carbenes from either alkynyl aryl/alkenyl sulfones or alkynyl sulfonate substrates. The reactivities of these donor- and acceptor-substituted carbenes are examined.
A Nucleophilic Strategy for Enantioselective Intermolecular α-Amination: Access to Enantioenriched α-Arylamino Ketones
Miles, Dillon H.,Guasch, Joan,Toste, F. Dean
, p. 7632 - 7635 (2015/07/02)
The enantioselective addition of anilines to azoalkenes was accomplished through the use of a chiral phosphoric acid catalyst. The resulting α-arylamino hydrazones were obtained in good yields and excellent enantioselectivities and provide access to enantioenriched α-arylamino ketones. A serendipitous kinetic resolution of racemic α-arylamino hydrazones is also described.
A new synthetic route for 1,2-diketo compounds using unexpected C-C bond cleavage by PCC
Bhosale, Shrikar M.,Momin, Aadil A.,Gawade, Rupesh L.,Puranik, Vedavati G.,Kusurkar, Radhika S.
, p. 5327 - 5330 (2012/11/07)
An efficient method has been established for the preparation of 1,2-diketones by unexpected C-C bond cleavage in 4-keto-2-hydroxy esters using pyridiniumchlorochromate (PCC).
A simple synthetic route to enantiopure α-hydroxy ketone derivatives by asymmetric hydrogenation
Sun, Tian,Zhang, Xumu
supporting information, p. 3211 - 3215 (2013/01/15)
High enantioselectivities (up to 99% ee) have been observed for the catalytic asymmetric hydrogenation of the α-ketone enol acetates. DuanPhos has been proved to be the most effective ligand for this reaction. The high yield and enantioselectivity of the asymmetric hydrogenation of the α-ketone enol acetates represents a feasible synthetic route to important pharmaceutical building blocks: α-hydroxy ketones. Copyright
Palladium-catalyzed carbonation-diketonization of terminal aromatic alkenes via carbon-nitrogen bond cleavage for the synthesis of 1,2-diketones
Wang, Azhong,Jiang, Huanfeng,Li, Xianwei
supporting information; experimental part, p. 6958 - 6961 (2011/10/02)
A palladium-catalyzed carbonation-diketonization reaction of terminal alkenes via carbon-nitrogen bond cleavage under an atmosphere of oxygen has been developed. A series of 1,2-diketones were readily prepared from the reaction of aromatic terminal alkenes with nitroalkanes.
New synthetic strategy for high-enantiopurity N-protected α-amino ketones and their derivatives by asymmetric hydrogenation
Sun, Tian,Hou, Guohua,Ma, Miaofeng,Zhang, Xumu
supporting information; experimental part, p. 253 - 256 (2011/04/16)
Asymmetric hydrogenation of α-dehydroamino ketones catalyzed by a rhodium-chiral phosphorus ligand complex (up to 99% ee, 1000 TON), represents an efficient approach to chiral α-amino ketones. The reduction of α-amino ketones catalyzed by palladium on carbon (Pd/C) leads to amphetamine precursors with quantitative yield and no significant enantioselectivity loss.
