- Photoinduced Diverse Reactivity of Diazo Compounds with Nitrosoarenes
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A diverse reactivity of diazo compounds with nitrosoarene in an oxygen-transfer process and a formal [2 + 2] cycloaddition is reported. Nitosoarene has been exploited as a mild oxygen source to oxidize an in situ generated carbene intermediate under visible-light irradiation. UV-light-mediated in situ generated ketenes react with nitosoarenes to deliver oxazetidine derivatives. These operationally simple processes exemplify a transition-metal-free and catalyst-free protocol to give structurally diverse α-ketoesters or oxazetidines.
- Roy, Sourav,Kumar, Gourav,Chatterjee, Indranil
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supporting information
p. 6709 - 6713
(2021/09/08)
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- Stereoselective Synthesis of Dihydrocoumarins via [1,2]-Phospha-Brook Rearrangement in Three-Component Coupling Reaction of α-Ketoesters, o-Quinone Methides, and Dialkyl Phosphites
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A highly regio- and diastereoselective approach for the synthesis of phosphate substituted dihydrocoumarins via Br?nsted base catalyzed [1,2]-phospha-Brook rearrangement is reported. The two-step, one-pot Michael addition of α-phosphonyloxy enolates proceeds by coupling of dialkyl phosphite and α-ketoesters to o-quinone methides, followed by an intramolecular cyclization, providing 3,4-dihydrocoumarin frameworks.
- Kaur, Ravneet,Singh, Dipak,Singh, Ravi P.
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p. 15702 - 15711
(2021/11/01)
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- Chemo- And diastereoselective synthesis of pyrrolidines from aroylformates and δ-tosylamino enones via P(NMe2)3-mediated reductive amination/base-catalyzed michael addition cascade
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A novel P(NMe2)3-mediated tandem (1 + 4) annulation between aroylformates and δ-tosylamino enones has been developed that affords a facile synthesis of functionalized pyrrolidines in moderate to excellent yields with exclusive chemoselectivity and high diastereoselectivity. Mechanistic investigation reveals that the reaction proceeds through an unprecedented P(NMe2)3-mediated reductive amination/base-catalyzed Michael addition cascade. The reaction herein also represents the first study of the reactivity patterns of the Kukhtin-Ramirez adducts toward ambiphilic nucleophile-electrophiles.
- Liu, Rongfang,Liu, Jialin,Cao, Jilei,Li, Ruifeng,Zhou, Rong,Qiao, Yan,Gao, Wen-Chao
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supporting information
p. 6922 - 6926
(2020/09/15)
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- Ambient and aerobic carbon-carbon bond cleavage toward α-ketoester synthesis by transition-metal-free photocatalysis
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The α-oxoesterification of the CC double bond in readily available enaminones enabling efficient synthesis of α-ketoesters is developed. The reactions showing general tolerance to the reactions of primary and secondary alcohols proceed well under air via Rose Bengal (RB)-based photocatalysis. Particularly, this mild synthetic method has been discovered to tolerate various polyhydroxylated substrates such as phenolic alcohol, diols and triols with an excellent selectivity of mono-oxoesterification. What is more noteworthy is that α-ketoester functionalized 16-dehydropregnenolone acetate resulting from the elaboration on a natural product has been obtained practically.
- Yu, Qing,Zhang, Yating,Wan, Jie-Ping
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supporting information
p. 3436 - 3441
(2019/06/24)
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- Diastereo- and Enantioselective Synthesis of Fluorine Motifs with Two Contiguous Stereogenic Centers
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The synthesis of chiral fluorine containing motifs, in particular, chiral fluorine molecules with two contiguous stereogenic centers, has attracted much interest in research due to the limited number of methods available for their preparation. Herein, we report an atom-economical and highly stereoselective synthesis of chiral fluorine molecules with two contiguous stereogenic centers via azabicyclo iridium-oxazoline-phosphine-catalyzed hydrogenation of readily available vinyl fluorides. Various aromatic, aliphatic, and heterocyclic systems with a variety of functional groups were found to be compatible with the reaction and provide the highly desirable product as single diastereomers with excellent enantioselectivities.
- Ponra, Sudipta,Rabten, Wangchuk,Yang, Jianping,Wu, Haibo,Kerdphon, Sutthichat,Andersson, Pher G.
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supporting information
p. 13878 - 13883
(2018/10/24)
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- α-Alkoxycarbonyl-α-hydroxy secondary amides from a carbamoylsilane and α-ketoesters
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The addition of N-methoxymethyl-N-organylcarbamoyl(trimethyl)silane to α-ketoesters in anhydrous toluene at 60 °C afforded α-alkoxycarbonyl-α-siloxy amides in high yields (75–96%). The methoxymethyl was used as an amino protecting group and could be easily converted into hydrogen atom by simple acid hydrolysis leading to α-alkoxycarbonyl-α- hydroxy secondary amides.
- Li, Weidong,Han, Yuling,Chen, Jianxin
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p. 5813 - 5819
(2017/09/05)
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- Copper(II)-Catalyzed Benzylic C(sp3)-H Aerobic Oxidation of (Hetero)Aryl Acetimidates: Synthesis of Aryl-α-ketoesters
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A straightforward method is developed in this paper for the synthesis of α-ketoesters through copper-catalyzed aerobic oxidation of (hetero)aryl acetimidates using molecular oxygen as a sustainable oxidant. The reaction represents the first example of the direct synthesis of aryl-α-ketoesters from arylacetimidates through the aerobic oxidation of a benzylic C(sp3)-H (CO) bond in moderate to good yield. This transformation occurs under mild reaction conditions with a wide range of substrates and utilizes a readily available oxidant and catalyst. The synthetic utility of this transformation is demonstrated through scaled-up synthesis. A plausible reaction mechanism is also proposed.
- Kumar, Yogesh,Jaiswal, Yogesh,Kumar, Amit
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p. 12247 - 12257
(2016/12/23)
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- Catalytic formal cycloadditions between anhydrides and ketones: Excellent enantio and diastereocontrol, controllable decarboxylation and the formation of adjacent quaternary stereocentres
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It has been shown for the first time that enolisable anhydrides can participate in highly efficient and diastereo/enantioselective additions to activated ketones. In these reactions the anhydride component formally acts (initially) as the nucleophilic component. These processes are promoted by novel, readily prepared urea-substituted cinchona alkaloid-derived catalysts at low loadings under mild conditions. Three classes of enolisable anhydride and three different types of activated ketone were shown to be compatible with the process-generating a diverse range of structurally distinct and densely functionalised lactone products with the formation of two new stereocentres, one of which is quaternary. In one example, a product incorporating two contiguous quaternary stereocentres (one all carbon) was formed with outstanding enantiocontrol. It has been shown in the case of glutaconic anhydride derivatives that the cycloaddtion process is reversible, and can be accompanied by decarboxylation and olefin isomerisation. Reaction conditions can be modified to give access to three types of product with good-excellent ee.
- Cornaggia, Claudio,Gundala, Sivaji,Manoni, Francesco,Gopalasetty, Nagaraju,Connon, Stephen J.
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supporting information
p. 3040 - 3046
(2016/03/19)
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- Development of a simple system for the oxidation of electron-rich diazo compounds to ketones
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Mild heating of diazo compounds in DMSO furnishes ketone products in moderate to excellent yields. The reaction is particularly effective on electron-rich substrates and exhibits high chemoselectivity, allowing for the use of diazo compounds containing additional oxidation-prone functional groups. This straightforward protocol offers an alternate route to synthetically useful α-ketoesters from readily available aryl diazoacetates.
- O'Connor, Nicholas R.,Bolgar, Peter,Stoltz, Brian M.
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supporting information
p. 849 - 851
(2016/02/05)
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- Chiral Frustrated Lewis Pairs Catalyzed Highly Enantioselective Hydrosilylations of 1,2-Dicarbonyl Compounds
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A highly enantioselective hydrosilylation of 1,2-dicarbonyl compounds was successfully realized for the first time utilizing the combination of tricyclohexylphosphine and chiral alkenylborane derived in situ from diyne as a frustrated Lewis pair catalyst. A variety of optically active α-hydroxy ketones and esters were obtained in 52-98% yields with 86-99% ee's.
- Ren, Xiaoyu,Du, Haifeng
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supporting information
p. 810 - 813
(2016/02/09)
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- A novel method for synthesis of α-keto esters with phenyliodine(III) diacetate
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A rapid and efficient synthesis of α-keto esters from β-ketonitriles using phenyliodine(III) diacetate is reported. This protocol gave α-keto esters in good yields. This is the first time to report the application of hypervalent iodine(III) reagents in the synthesis of α-keto esters. A plausible reaction mechanism is proposed.
- Xie, Yuanyuan,Liu, Jiwei,Huang, Yingyi,Yao, Lixia
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supporting information
p. 3793 - 3795
(2015/06/08)
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- Highly homogeneous stereocontrolled construction of quaternary hydroxyesters by addition of dimethylzinc to α-ketoesters promoted by chiral perhydrobenzoxazines and B(OEt)3
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A highly efficient enantioselective addition of Me2Zn to α-ketoesters, assisted by a chiral perhydro-1,3-benzoxazine ligand, is described. This novel catalytic system offers homogeneous elevated enantioselectivities in the preparation of α-hydroxyesters that bear a quaternary stereocenter, with a minor dependence on electronic and steric effects when aromatic, heteroaromatic, or aliphatic α-ketoesters are employed. The catalyst can be recovered and reused without loss of activity.
- Infante, Rebeca,Nieto, Javier,Andres, Celia
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supporting information; experimental part
p. 4375 - 4379
(2012/05/20)
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- Direct synthesis of α-keto esters from ethylbenzenes using 48% aqueous HBr by aerobic visible light photooxidation
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We report that ethylbenzenes can be directly oxidized to the corresponding -keto esters with molecular oxygen in the presence of 48% aqueous HBr under visible light irradiation. This synthetic procedure is the first example for direct preparation of the corresponding α-keto esters from ethylbenzenes. Georg Thieme Verlag Stuttgart - New York.
- Tada, Norihiro,Ban, Kazunori,Nobuta, Tomoya,Hirashima, Shin-Ichi,Miura, Tsuyoshi,Itoh, Akichika
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experimental part
p. 1381 - 1384
(2011/07/31)
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- Muscarinic receptor antagonists
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The present invention relates generally to muscarinic receptor antagonist, which are useful, among other uses, for the treatment of various diseases of the respiratory, urinary and gastrointestinal systems mediated through muscarinic receptors. The invention also relates to the process for the preparation of disclosed compounds, pharmaceutical compositions containing the disclosed compounds and the method for treating diseases mediated through muscarinic receptors. Also provided herein are pharmaceutical composition comprising one or more muscarinic receptor antagonists and at least one other active ingredients include, but are not limited to, corticosteroids, beta agonists, leukotriene antagonists, 5-lipoxygenase inhibitors, anti-histamines, antitussives, dopamine receptor antagonists, chemokine inhibitors, p38 MAP Kinase inhibitors, and PDE-IV inhibitors.
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Page/Page column 9
(2009/12/24)
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- MUSCARINIC RECEPTOR ANTAGONISTS
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The present invention relates generally to muscarinic receptor antagonist, which are useful, among other uses, for the treatment of various diseases of the respiratory, urinary and gastrointestinal systems mediated through muscarinic receptors. The invention also relates to the process for the preparation of disclosed compounds, pharmaceutical compositions containing the disclosed compounds and the method for treating diseases mediated through muscarinic receptors. Also provided herein are pharmaceutical composition comprising one or more muscarinic receptor antagonists and at least one other active ingredients include, but are not limited to, corticosteroids, beta agonists, leukotriene antagonists, 5-lipoxygenase inhibitors, anti-histamines, antitussives, dopamine receptor antagonists, chemokine inhibitors, p38 MAP Kinase inhibitors, and PDE-IV inhibitors.
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Page/Page column 6-7
(2010/01/31)
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- CeCl3·7H2O: An effective additive in ru-catalyzed enantioselective hydrogenation of aromatic α-ketoesters
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(Chemical Equation Presented) In the presence of catalytic amounts of CeCl3·7H2O, [RuCl(benzene)(S)-SunPhos]Cl is a highly effective catalyst for the asymmetric hydrogenation of aromatic α-ketoesters. A variety of ethyl α-hydroxy-α-arylacetates have been prepared in up to 98.3% ee with a TON up to 10 000. Challenging aromatic α-ketoesters with ortho substituents are also hydrogenated with high enantioselectivities. The addition of CeCl3·7H2O not only improves the enantioselectivity but also enhances the stability of the catalyst. The ratio of CeCl3·7H2O to [RuCl(benzene)(S)-SunPhos]Cl plays an important role in the hydrogenation reaction with a large substrate/catalyst ratio.
- Meng, Qinghua,Sun, Yanhui,Ratovelomanana-Vidal, Virginie,Genet, Jean Pierre,Zhang, Zhaoguo
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p. 3842 - 3847
(2008/09/21)
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- 3,6-DISUBSTITUTED AZABICYCLO [3.1.0] HEXANE DERIVATIVES AS MUSCARINIC RECEPTOR ANTAGONISTS
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The present invention generally relates to muscarinic receptor antagonists, which are useful, among other uses, for the treatment of various diseases of the respiratory, urinary and gastrointestinal systems mediated through muscarinic receptors. The invention also relates to the process for the prepration of disclosed compounds, pharmaceutical compositions containing the disclosed compounds, and the methods for treating diseases mediated through muscarinic receptors.
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Page/Page column 19
(2008/06/13)
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- COUPLING OF ORGANOTIN REAGENTS WITH ARYL, ACYL AND HETEROARYL HALIDES: SYNTHESIS OF PYRIDAZINE AND QUINOXALONE DERIVATIVES
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Couplin of organotin reagents Bu3SnAr (Ar = 2- or 3-thienyl, 2- or 3-pyridyl) with ClCOCH2CH2CO2Et in the presence of PdCl(CH2Ph)(PPh3)2 yields β-ketoesters ArCOCH2CH2CO2Et which were converted with hydrazine hydrate into 6-substituted 4,5-dihydropyridazin-3(2H)-ones, and thence to 3-halogeno-6-substituted pyridazines.The latter also couple under similar conditions with Bu3SnAr to yield 3-heteroarylpyridazines.With catalysts, coupling of ClCOCO2Et and Bu3SnAr proceeds with loss of carbon monoxide giving ArCO2Et, but without catalyst ArCOCO2Et is formed from which the3-heteroarylquinoxalin-3-one is prepared.The reactions of Bu3SnAr with 4-XC6H4Br (X = H,-OMe, -CN, -NO2) are also described.
- Powell, Paul,Sosabowski, Michael H.
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p. 2422 - 2434
(2007/10/03)
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- A MILD, RAPID, AND CONVENIENT ESTERIFICATION OF α-KETO ACIDS
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A new method for the esterification of α-keto acids with alkyl chloroformates is described, which is compatible with many functional groups.
- Domagala, John M.
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p. 4997 - 5000
(2007/10/02)
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