- Palladium Catalyzed Ring Expansion Reaction of Isoxazolones with Isocyanides: Synthesis of 1,3-Oxazin-6-One Derivatives
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A palladium catalyzed ring expansion reaction of isoxazolones with isocyanides was disclosed. In the reaction, a cascade process involving ring-opening/cyclization was suggested. The reaction features high atomic economy due to no elimination of CO2 occurred. Moreover, products obtained demonstrate aggregation-induced emission properties with relatively high solid-state emission efficiencies. (Figure presented.).
- Zhu, Yi-Ming,Zhang, Wan,Li, Hongkun,Xu, Xiao-Ping,Ji, Shun-Jun
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p. 808 - 818
(2020/12/03)
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- N-Heterocyclic carbene-catalyzed deaminative cross-coupling of aldehydes with Katritzky pyridinium salts
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By employing an N-heterocyclic carbene (NHC) catalyst, we developed a versatile catalytic system that enables deaminative cross-coupling reactions of aldehydes with redox-active pyridinium salts. Katritzky pyridinium salts behave as single-electron oxidants capable of generating alkyl radicals enabled by the redox properties of the enolate form of Breslow intermediates. The resultant alkyl radical undergoes efficient recombination with the NHC-bound aldehyde-derived carbonyl carbon radical for the formation of a C-C bond. The mild and transition metal-free reaction conditions tolerate a broad range of functional groups, and its utility has been further demonstrated by the modification of a series of peptide feedstocks and application to the three-component dicarbofunctionalization of olefins.
- Kim, Inwon,Im, Honggu,Lee, Hyeonyeong,Hong, Sungwoo
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p. 3192 - 3197
(2020/04/08)
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- Radical Chlorodifluoromethylation: Providing a Motif for (Hetero)arene Diversification
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A method for the radical chlorodifluoromethylation of (hetero)arenes using chlorodifluoroacetic anhydride is reported. This operationally simple protocol proceeds under mild photochemical conditions with high functional group compatibility and complements the large body of literature for the trifluoromethylation of (hetero)arenes. Introduction of the chlorodifluoromethyl motif enables rapid diversification to a wide array of aromatic scaffolds. This work showcases the chlorodifluoromethyl group as an attractive entryway to otherwise synthetically challenging electron-rich difluoromethyl(hetero)arenes. Furthermore, facile conversion of the CF2Cl moiety into the corresponding aryl esters, gem-difluoroenones, and β-keto-esters is demonstrated.
- McAtee, Rory C.,Beatty, Joel W.,McAtee, Christopher C.,Stephenson, Corey R. J.
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p. 3491 - 3495
(2018/06/26)
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- Asymmetric Alkynylation of β-Ketoesters and Naphthols Promoted by New Chiral Biphenylic Iodanes
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The preparation of new chiral biphenylic λ3-iodane reagents bearing transferable alkynyl ligands is described. These reagents transfer their carbon-based ligands onto β-ketoesters with an enantiomeric excess (ee) up to 68 %, and most remarkably, enable the dearomative alkynylation of naphthols in good to high yields up to 84 % ee.
- Companys, Simon,Peixoto, Philippe A.,Bosset, Cyril,Chassaing, Stefan,Miqueu, Karinne,Sotiropoulos, Jean-Marc,Pouységu, Laurent,Quideau, Stéphane
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supporting information
p. 13309 - 13313
(2017/10/05)
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- A General and Robust Method for the Preparation of (E)- and (Z)-Stereodefined Fully Substituted Enol Tosylates: Promising Cross-Coupling Partners
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A robust method for preparing (E)- and (Z)-stereodefined fully substituted enol tosylates is described. α-Substituted β-keto esters undergo (E)-selective enol tosylations using TsCl-Me2N(CH2)6NMe2 as the reagent (method A, 13 examples; 63-96%) and (Z)-selective enol tosylations using TsCl-TMEDA-LiCl as the reagent (method B, 13 examples; 62-99%). A plausible mechanism for the (E)- and (Z)-enol tosylation selectivity is proposed. A 1H NMR monitoring experiment revealed that TsCl coupled with TMEDA formed a simple N-sulfonylammonium intermediate.
- Ashida, Yuichiro,Sato, Yuka,Honda, Atsushi,Nakatsuji, Hidefumi,Tanabe, Yoo
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supporting information
p. 4072 - 4080
(2016/11/26)
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- Morita-Baylis-Hillman adducts as building blocks of heterocycles: a simple approach to 4-substituted pyrazolones, and mechanism investigation via ESI-MS(/MS)
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Abstract We describe herein an efficient approach for the preparation of 4-substituted 2,3-dihydro-1H-pyrazol-3-ones starting from Morita-Baylis-Hillman adducts. These heterocycles were obtained in two or three steps as single isomers with moderate to goo
- Barcelos, Rosimeire C.,Zeoly, Lucas A.,Rodrigues, Manoel T.,Ferreira, Bruno R. V.,Eberlin, Marcos N.,Coelho, Fernando
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p. 1557 - 1570
(2015/02/19)
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- Tert -butyl peroxybenzoate-promoted α-methylation of 1,3-dicarbonyl compounds
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A tert-butyl peroxybenzoate (TBPB)-promoted direct α-methylation of 1,3-dicarbonyl compounds has been developed, providing α-methyl derivatives in moderate to good yields. In this procedure, TBPB plays a dual role, serving as both the methyl source and radical initiator. This work represents a key complement to the traditional α-methylation of 1,3-dicarbonyl compounds using methyl iodide.
- Guo, Songjin,Wang, Qian,Jiang, Yan,Yu, Jin-Tao
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p. 11285 - 11289
(2015/01/08)
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- Rhodium-catalyzed hydroaroylation of α,β-unsaturated esters using aroyl chlorides and Et2MeSiH
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Hydroaroylation of methyl acrylate 2a to give the α-aroyl esters 4 took place in the three-component reaction of 2a, aroyl chlorides 1, and Et 2MeSiH in the presence of 1 mol % of [Rh(cod)(PR3) 2]OTf (cod = 1,5-cyclooctadi
- Muraoka, Takako,Hiraiwa, Eiji,Abe, Minami,Ueno, Keiji
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supporting information
p. 4309 - 4312
(2013/07/26)
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- Regio-and enantioselective bioreduction of methyleneketoesters using both polymeric resin and cellulose matrix
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Methyleneketoesters were prepared in >90% yield by performing an IBX oxidation of Morita-Baylis-Hillman adducts. A methodology was developed to achieve methyl 3-aryl-3-keto-2-methylenepropanoate reduction using a screening of yeast strains in three different reaction procedures to obtain products with both high yield and diastereoselectivity. The reactions conducted in water provided inferior yields (50%) for substrates 2b-c. Employing Amberlite XAD7HP which was a substrate reservoir that also immediately extracted the products from the reaction medium after their formation, syn-4a-c and anti-4a-c were isolated in 60-70% yield, with high stereoselectivity (98-99% ee). The best results were obtained using substrates adsorbed on filter paper which provided products yields above 70%, a 99% ee and a diastereomoeric ratio (syn-4: anti-4) 9:1. Cellulose matrix has excellent potential to be successfully employed in general biocatalytic reactions.
- Chaves, Michel R.B.,Moran, Paulo J.S.,Rodrigues, J. Augusto R.
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- A new mild method for the C-acylation of ketone enolates. a convenient synthesis of β-keto-esters,-thionoesters, and-thioesters
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A new method for ketone enolate C-acylation is described which utilizes alkyl pentafluorophenylcarbonates, thiocarbonates, and thionocarbonates as the reactive acylating agents, and MgBr2·Et2O, DMAP, and i-Pr2NEt as the reagents for enolization. A wide range of ketones have been observed to undergo clean C-acylation via this protocol.
- Hale, Karl J.,Grabski, Milosz,Flasz, Jakub T.
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supporting information
p. 370 - 373
(2013/03/13)
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- Azidation of β-keto esters and silyl enol ethers with a benziodoxole reagent
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The efficient azidation of β-keto esters and silyl enol ethers using a benziodoxole-derived azide transfer reagent is reported. The azidation of cyclic β-keto esters could be achieved in up to quantitative yields in the absence of any catalyst. In the case of less reactive linear β-keto esters and silyl enol ethers, complete conversion and good yields could be obtained by using a zinc catalyst.
- Vita, Maria Victoria,Waser, Jerome
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supporting information
p. 3246 - 3249
(2013/07/26)
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- Reductive Reformatsky-Honda reaction of α,β-unsaturated esters: Facile formation of 1,3-dicarbonyl compounds and β-hydroxy esters
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The reaction of tris(triphenylphosphine)rhodium chloride [RhCl(PPh 3)3] with diethylzinc (Et2Zn) easily afforded a rhodium-hydride complex that effects the 1,4-reduction of α,β- unsaturated esters to give rhodium enolates. Formation of the rhodium enolate is followed by transmetalation with the zinc species to give a Reformatsky-type reagent, and this reacts with various acid chlorides at the α-position to give β-keto esters. The Reformatsky-type reagent also reacts with various electrophiles such as aldehydes, ketones and acid anhydrides to give the corresponding products in which the electrophiles were introduced reductively at the α-position of α,β-unsaturated esters. Copyright
- Sato, Kazuyuki,Isoda, Motoyuki,Ohata, Shizuka,Morita, Shuhei,Tarui, Atsushi,Omote, Masaaki,Kumadaki, Itsumaro,Ando, Akira
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supporting information; experimental part
p. 510 - 514
(2012/04/23)
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- Substrate range of the titanium TADDOLate catalyzed asymmetric fluorination of activated carbonyl compounds
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The substrate range of the [TiCl2(TADDOLate)] (TADDOL=α,α,α′,α′-tetraaryl-1,3-dioxolane-4, 5-dimethanol)-catalyzed asymmetric α-fluorination of activated β-carbonyl compounds has been investigated. Optimal conditions for catalysis are characterized by using 5 mol-% of TiCl2(naphthalen-1- yl)-TADDOLate) as catalyst in a saturated (0.14 mol/l) MeCN solution of F-TEDA (1-(chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis- [tetrafluoroborate]) at room temperature. A series of α-methylated β-keto esters (3-oxobutanoates, 3-oxopentanoates) with bulky benzyl ester groups (60-90% ee) or phenyl ester (67-88% ee) have been fluorinated readily, whereas α-acyl lactones were also readily fluorinated, but gave lower inductions (13-46% ee). Double stereochemical differentiation in β-keto esters with chiral ester groups raised the stereoselectivity to a diastereomeric ratio (dr) of up to 96.5:3.5. For the first time, β-keto S-thioesters were asymmetrically fluorinated (62-91.5% ee) and chlorinated (83% ee). Lower inductions were observed in fluorinations of 1,3-diketones (up to 40% ee) and β-keto amides (up to 59% ee). General strategies for preparing activated β-carbonyl compounds as important model substrates for asymmetric catalytic α-functionalizations are presented (>60 examples). Copyright
- Bertogg, Andreas,Hintermann, Lukas,Huber, Dominique P.,Perseghini, Mauro,Sanna, Maria,Togni, Antonio
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experimental part
p. 353 - 403
(2012/05/07)
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- Synthesis and biological activity of new (E)-α-(Methoxyimino) benzeneacetate derivatives containing a substituted pyrazole ring
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Strobilurins are one of the most important classes of agricultural fungicides. To discover new strobilurin analogues with high activity, a series of new strobilurin derivatives containing a substituted pyrazole in the side chain were synthesized and their biological activities were tested. The compounds were identified by 1H nuclear magnetic resonance, infrared, and elemental analysis. The test results indicated that the compounds exhibited strong fungicidal activities against Pyricularia oryzae, Phytophthora infestans, Pseudoperonospora cubenssi, and Erysiphe graminis. The relationship between structure and biological activity is discussed in terms of the effects of the substituents on the pyrazole ring. The present work demonstrates that strobilurin analogues with a 3-(substituted phenyl)-1 H-pyrazol-5-oxy side chain can be used as possible lead compounds for the development of potential agrochemicals.
- Li, Miao,Liu, Chang-Ling,Yang, J.I.-Chun,Zhang, Jin-B.O.,Li, Zhi-Nian,Zhang, Hong,Li, Zheng-Ming
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experimental part
p. 2664 - 2667
(2011/08/05)
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- Palladium-catalyzed carbonylation/acyl migratory insertion sequence
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Chemical Equation Presented On the move: A palladium-catalyzed reaction of aryl iodides, diazo compounds or N-tosylhyd razones, and carbon monoxide affords β-oxo esters or ketones/ enones (see scheme; DCE = l,2-dichloroethane). The products are delivered with high efficiency through the title sequence.
- Zhang, Zhenhua,Liu, Yiyang,Gong, Mingxing,Zhao, Xiaokun,Zhang, Yan,Wang, Jianbo
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supporting information; experimental part
p. 1139 - 1142
(2010/05/02)
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- Photoaddition reactions of 1,2-diketones with silyl ketene acetals. Formation of β-hydroxy-γ-ketoesters
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(Chemical Equation Presented) Photochemical reactions taking place between 1,2-diketones and silyl ketene acetals and their excited state reaction mechanisms have been explored. Irradiation of benzene, acetone, or acetonitrile solutions containing 1,2-diketones and silyl ketene acetals is observed to promote formation of 1,4-dioxenes, resulting from [4 + 2]-cycloaddition, oxetanes, arising by Paterno-Buchi processes, and β-hydroxy-γ- ketoesters, generated by SET-promoted Claisen-type condensation. These competitive pathways leading from the excited states of the 1,2-diketones to these products are influenced by solvent polarity and the nature of the silyl ketene acetal and 1,2-diketone. The Claisen-type condensation process, following an SET desilylation pathway and predominating when the photoreactions are carried out in the polar solvent acetonitrile, represents an efficient method to prepare a variety of diversely substituted β-hydoxy-γ-ketoesters.
- Dae, Won Cho,Lee, Hyang-Yeol,Sun, Wha Oh,Jung, Hei Choi,Hea, Jung Park,Mariano, Patrick S.,Ung, Chan Yoon
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p. 4539 - 4547
(2008/09/20)
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- Reductive Ti-crossed Claisen condensation between methyl α-bromocarboxylates and acid chlorides utilizing a TiCl 4-PPh3-N-methylimidazole reagent
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Reductive Ti-crossed Claisen condensation between methyl α-bromocarboxylates and acid chlorides utilizing a TiCl 4-PPh3-N-methylimidazole reagent proceeded smoothly to give the α-monosubstituted and thermodynamically unfavorable α,α-
- Iida, Akira,Nakazawa, Syogo,Nakatsuji, Hidefumi,Misaki, Tomonori,Tanabe, Yoo
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- An electrochemical coupling of organic halide with aldehydes, catalytic in chromium and nickel salts. the Nozaki-Hiyama-Kishi reaction.
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[reaction: see text] Electrochemical arylation of arenecarboxaldehydes using an iron sacrificial anode in the presence of chromium and nickel catalysts afforded the corresponding arylated secondary alcohols in moderate to good yields. The chromium and nickel salts as catalysts are obtained by oxidation of a stainless steel rod during a preelectrolysis in 7% and 3%, respectively. The process was also applied to the addition of vinyl halide, allyl acetate, or alpha-chloroester to aromatic aldehydes.
- Durandetti,Nedelec,Perichon
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p. 2073 - 2076
(2007/10/03)
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- From allylic alcohols to saturated carbonyls using Fe(CO)5 as catalyst: Scope and limitation studies and preparation of two perfume components
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The direct conversion of allylic alcohols to saturated carbonyls, using Fe(CO)5 as a catalyst, offers good synthetic potential. Mono-, di- and even trisubstituted alkenes bearing various alkyl, aryl and electronwithdrawing groups on the allylic system give good to excellent yields of rearranged products. Limitations occur mainly with polyunsaturated derivatives. This reaction was applied to a short and efficient synthesis of cyclamen aldehyde and foliaver.
- Cherkaoui, Hassan,Soufiaoui, Mohammed,Grée, René
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p. 2379 - 2383
(2007/10/03)
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- RuCl2(PPh3)3 catalyzed isomerization of the Baylis-Hillman adducts
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RuCl2(PPh3)3 catalyzed isomerization of the Baylis-Hillman adducts i.e. methyl 3-aryl-3-hydroxy-2-methylenepropanoates to methyl 3-aryl-2- methyl-3-oxopropanoates has been described.
- Basavaiah, Deevi,Muthukumaran, Kannan
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p. 713 - 719
(2007/10/03)
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- Lanthanoid Complex as a Novel Carbon Dioxide Carrier for the Carboxylation of Active Methylene Compounds under Mild Conditions
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A lanthanoid complex, formed by the addition of a lanthanoid alkoxide to an isocyanate, serves as a novel carbon dioxide carrier for the rapid carboxylation of active methylene compounds under mild conditions.
- Abe, Hiroshi,Inoue, Shohei
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p. 1197 - 1198
(2007/10/02)
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- New method of zinc activation by electrochemistry: synthetic applications to the Blaise reaction
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A new electrochemical zinc metal activation method based on the cathodic reduction of a catalytic amount of zinc bromide in the presence of a zinc anode is described.This procedure is applied to the coupling of α-bromoesters with nitriles, and affords β-ketoesters in good yield.
- Zylber, N.,Zylber, J.,Rollin, Y.,Dunach, E.,Perichon, J.
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- Electrochemical activation of zinc in the coupling reaction of α-bromoesters with carbonyl compounds
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The Reformatsky reaction has been examined using a mild and effective method of electrochemical zinc activation, based on the cathodic reduction of a catalytic amount of zing bromide in acetonitrile.
- Rollin, Y.,Gebehenne, C.,Derien, S.,Dunach, E.,Perichon, J.
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- A Practical Synthetic Method for β-Ketosters from Ketones
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A practical, simple, one-pot synthesis of β-ketoesters (3) from ketones (1) via bis(methylthio)ketene acetals (4) was achieved. Keywords---β-ketoester; bis(methylthio)ketene acetals; C-alkoxycarbonylation; ketone; carbon disulfide
- Tomozane, Hideo,Takeuchi, Yasuo,Yamato, Masatoshi
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p. 401 - 404
(2007/10/02)
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- Reaction of 2,2-Dimethyl-1,3-dioxin-4-one Derivatives with Pyridinium (Isoquinolinium) Methylides and Cyano Compounds
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Cycloaddition of acylketenes (2) to 1,2- and 1,3-dipolar compounds was investigated.The thermal reaction of 1,3-dioxin-4-ones (1) with isoquinolinium phenylacylide (11) gave the aromatized pyrroloisoquinolines (12-15).The reaction of 1 with pyridin
- Sato, Masayuki,Kanuma, Norio,Kato, Tetsuzo
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p. 106 - 116
(2007/10/02)
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- Mechanism of the Photochemical and Thermal Wolff Rearrangement of 2-Diazo-1,3-dicarbonyl Compounds
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Thermolysis and photolysis of diazo-1,3-dicarbonyl compounds were investigated as a fuction of methanol concentration.As the methanol concentration decreased, methyl group migration increased concomitant with the suppresion of O-H insertion into methanol, whereas aryl group migration was essentially uanaltered with the methanol concentration.The results are interpreted as indicating that aryl migration occurs directly from the excited state of diazo compounds, but that methyl migration takes place un the singlet carbene in competition with O-H insertion.
- Tomioka, Hideo,Hayashi, Norihiro,Asano, Tsuneo,Izawa, Yasuji
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p. 758 - 761
(2007/10/02)
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- A Short Synthesis of the 4-Demethoxy-11-deoxyanthracycline Skeleton. Regiospecific Enolate C-Carboxylation with Carbon Oxysulfide
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Regiospecific C-carboxylation of enolate 2 and COS followed by methylation (CH3I) and cuprous triflate cyclization results in a tetracyclic product 9 which can be converted into 11-deoxyanthracyclines.
- Vedejs, E.,Nader B.
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p. 3193 - 3195
(2007/10/02)
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- The Allopolarization Principle and its Applications, IV. Substituent Effects in the Methylation of Enolate Anions
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The ratio of O- and C-methylated products in the reaction of the sodium salts of acetophenones 1, propiophenones 3, phenylacetones 5, β-dicarbonyl compounds 12, α-cyanocarbonyl compounds 13, acetaldehyde, propionaldehyde, and diethylketone with dimethyl sulfate, methyl iodide, and trimethyl phosphate in HMPTA has been determined with regard to the effect of substituents.In some cases the influence of solvents, concentration and temperature has also been studied.
- Gompper, Rudolf,Vogt, Hans-Hubert
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p. 2866 - 2883
(2007/10/02)
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