- Trisulfur-Radical-Anion-Triggered C(sp2)-H Amination of Electron-Deficient Alkenes
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A trisulfur-radical-anion (S3˙-)-triggered C(sp2)-H amination of α,β-unsaturated carbonyl derivatives with simple amines has been demonstrated. This protocol provides convenient access to a variety of synthetically valuable N-unprotected and secondary β-enaminones with absolute Z selectivity and tertiary β-enaminones with E selectivity. Mechanistic probe and electronic structure theory calculations suggest that S3˙- initiates the nucleophilic attacks via a thiirane intermediate.
- Nguyen, Khang X.,Nguyen, Thao T.,Nguyen, Tung T.,Pham, Hoai T. B.,Pham, Phuc H.,Phan, Nam T. S.,Wang, Haobin,Yang, Chou-Hsun
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supporting information
p. 9751 - 9756
(2020/12/21)
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- Solvent-Controlled Synthesis of Thiocyanated Enaminones and 2-Aminothiazoles from Enaminones, KSCN, and NBS
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An effective and simple solvent-controlled synthesis of thiocyanated enaminones and 2-aminothiazoles has been demonstrated from enaminones, potassium thiocyanate, and N-bromosuccinimide. This process features mild reaction conditions, simple and easy oper
- Chen, Xue,Cuan, Xiaodan,Duan, Xiyan,Li, Huimin,Liu, Kun,Liu, Xiaojing,Wang, Junqin,Wang, Lin,Zhou, Huiyun
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- PhIO/Et3N ? 3HF-Mediated Formation of Fluorinated 2H-Azirines via Domino Fluorination/Azirination Reaction of Enamines
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A variety of enamine carboxylic esters and enaminones were converted to the biologically interesting fluorinated 2H-azirines through reactions with PhIF2 generated in situ by PhIO and Et3N ? 3HF in 1,2-dichroloethane, which features the hypervalent iodine reagents-mediated introduction of fluorine atom and formation of the 2H-azirine skeleton under metal-free conditions. The domino reaction is postulated to proceed via a PhIF2-mediated oxidative fluorination and a subsequent azirination of the fluorinated enamine intermediates. (Figure presented.).
- Zhang, Yong,Zhao, Xiaoyuan,Zhuang, Chen,Wang, Senlin,Zhang-Negrerie, Daisy,Du, Yunfei
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p. 2107 - 2112
(2018/04/19)
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- Quinone-Fused Pyrazoles through 1,3-Dipolar Cycloadditions: Synthesis of Tricyclic Scaffolds and in vitro Cytotoxic Activity Evaluation on Glioblastoma Cancer Cells
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A novel and straightforward synthesis of highly substituted isoquinoline-5,8-dione fused tricyclic pyrazoles is reported. The key step of the synthetic sequence is a regioselective, Ag2CO3 promoted, 1,3-dipolar cycloaddition of C-heteroaryl-N-aryl nitrilimines and substituted isoquinoline-5,8-diones. The broad functional group tolerability and mild reaction conditions were found to be suitable for the preparation of a small library of compounds. These scaffolds were designed to interact with multiple biological residues, and two of them, after brief synthetic elaborations, were analyzed by molecular docking studies as potential anticancer drugs. In vitro studies confirmed the potent anticancer effects, showing promising IC50 values as low as 2.5 μm against three different glioblastoma cell lines. Their cytotoxic activity was finally positively correlated to their ability to inhibit PI3K/mTOR kinases, which are responsible for the regulation of diverse cellular processes in human cancer cells.
- Bertuzzi, Giulio,Crotti, Simone,Calandro, Pierpaolo,Bonini, Bianca Flavia,Monaco, Ilaria,Locatelli, Erica,Fochi, Mariafrancesca,Zani, Paolo,Strocchi, Elena,Mazzanti, Andrea,Chiariello, Mario,Franchini, Mauro Comes
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p. 1744 - 1750
(2018/09/11)
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- Amido Complexes of Iridium with a PNP Pincer Ligand: Reactivity toward Alkynes and Hydroamination Catalysis
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The pincer ligand HN(CH2CH2PPh2)2 (1; PNHP) reacted with [{Ir(μ-X)(cod)}2] (X = Cl, OMe), affording complexes [fac-(PNHP)Ir(cod)]Cl (2) and [fac-(PNP)Ir(cod)] (3), respectively. The X-ray molecular structure of 2 showed that the PNP ligand coordinates in a facial fashion, with the N atom in an axial site and both P atoms coordinated in the equatorial plane. Compound 1 is able to protonate the hydroxo bridges in the complex [{Ir(μ-OH)(coe)2}2] forming the new amido complex [mer-(PNP)Ir(coe)] (4). Complex 4 is an extremely air sensitive compound, as confirmed by the isolation of the oxo complex [mer-(PNP)Ir(σ2-O2)] (8) from its interaction with air. Protonation of 4 with HBF4 afforded the corresponding amino complex [mer-(PNHP)Ir(coe)]BF4 (5), whose molecular structure enlightened by X-ray crystallography confirmed the PNP ligand to be coordinated in a meridional fashion. The coe ligand in 4 is tightly bonded to iridium; however, under an atmosphere of ethylene at 60 °C or with acrylonitrile at 70 °C complex 4 exchanges the olefin, affording compounds [mer-(PNP)Ir(σ2-C2H4)] (6) and [mer-(PNP)Ir(σ2-C2H3CN)] (7), respectively. Interaction of 4 with alkynes depends on the nature of the substrate; therefore, methyl phenylpropiolate reacted with 4, affording the adduct [mer-(PNP)Ir(σ2-PhCCC(O)OMe)] (9), while the parent acetylene undergoes a double C-H activation, affording the Ir(III) complex [fac-(PNHP)IrH(Ca‰?CH)2] (10). A DFT theoretical analysis of this transformation supports a metal-ligand cooperation mechanism. The reaction starts by deprotonation of an alkyne moiety by the PNP ligand followed by oxidative addition of the C-H bond to the metal of a second alkyne molecule. Additionally, we have tested complex 4 as a catalyst for the addition of gaseous ammonia to activated unsaturated substrates. A DFT theoretical analysis disclosed the operative mechanism on these organic transformations, which starts with a nucleophilic attack of ammonia to the bound alkyne, hydrogen migration to the metal, and reductive elimination steps.
- Hermosilla, Pablo,López, Pablo,García-Ordunìa, Pilar,Lahoz, Fernando J.,Polo, Víctor,Casado, Miguel A.
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p. 2618 - 2629
(2018/08/21)
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- Formation of functionalized 2H-azirines through phio-mediated trifluoroethoxylation and azirination of enamines
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A variety of enaminones and enamine carboxylic esters were converted to trifluoroethoxylated 2H-azirines through reactions with PhIO in trifluoroethanol (TFE). The cascade reaction is postulated to proceed via a PhIO-mediated oxidative trifluoroethoxylation and a subsequent azirination of the α-trifluoroethoxylated enamine intermediates.
- Sun, Xiaoqian,Lyu, Youran,Zhang-Negrerie, Daisy,Du, Yunfei,Zhao, Kang
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p. 6222 - 6225
(2014/01/17)
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- Enantioselective hydrogenation of β-dehydroamino acids on a cinchonidine-modified palladium catalyst
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Enantioselective hydrogenation of (Z)-β-dehydroamino acids on a cinchonidine-modified Pd/Al2O3 catalyst was explored. Comparative studies by using (Z)-β-dehydroamino acids and esters identified that the carboxylic group in dehydroamino acids was essentially important to get enantioselectivities (33% for aryl substituted and 46% for alkyl substituted β-dehydroamino acids). This result extended the range of enantioselective hydrogenation of α,β-unsaturated carboxylic acids on chirally modified Pd catalysts and offered a new approach to synthesize optically active β-amino acids.
- Chen, Chunhui,Zhan, Ensheng,Li, Yong,Shen, Wenjie
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p. 117 - 121
(2013/09/23)
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- Stereochemistry and mechanism of a microbial phenylalanine aminomutase
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The stereochemistry of a phenylalanine aminomutase (PAM) on the andrimid biosynthetic pathway in Pantoea agglomerans (Pa) is reported. PaPAM is a member of the 4-methylidene-1H-imidazol-5(4H)-one (MIO)-dependent family of catalysts and isomerizes (2S)-α-phenylalanine to (3S)-β-phenylalanine, which is the enantiomer of the product made by the mechanistically similar aminomutase TcPAM from Taxus plants. The NH2 and pro-(3S) hydrogen groups at Cα and Cβ, respectively, of the substrate are removed and interchanged completely intramolecularly with inversion of configuration at the migration centers to form β-phenylalanine. This is a contrast to the retention of configuration mechanism followed by TcPAM.
- Ratnayake, Nishanka Dilini,Wanninayake, Udayanga,Geiger, James H.,Walker, Kevin D.
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p. 8531 - 8533
(2011/07/29)
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- A novel synthesis of N-unsubstituted β-enamino thioesters from 3-arylisoxazoles and 3-aryl-5-phenylthio-2-isoxazolines
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A novel procedure for the synthesis of N-unsubstituted β-enamino thioesters, (Z)-S-phenyl 3-amino-3-arylprop-2-enethioates, from 3-arylisoxazoles or 3-aryl-5-phenylthio-2-isoxazolines is described and a plausible mechanism for the reaction is proposed. Some examples of conversion of one β-enamino thioester [(Z)-S-phenyl 3-amino-3-phenylprop-2-enethioate] into N-unsubstituted β-enaminoacyl derivatives (β-enamino esters, β-enamino amides, and β-keto amides) are also reported. Georg Thieme Verlag Stuttgart - New York.
- Vitale, Paola,Di Nunno, Leonardo,Scilimati, Antonio
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experimental part
p. 3195 - 3203
(2010/10/21)
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- Detection and elimination of product inhibition from the asymmetric catalytic hydrogenation of enamines
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(Chemical Equation Presented) The catalytic asymmetric hydrogenation of enamine amides and esters with catalyst Rh-1a, prepared from ferrocenyl based ligand 1a or 1b and [(COD)RhCl]2, has been shown through kinetic studies to suffer from product inhibition. Enamine ester substrates have also been shown to be incompatible with the amine products of the reaction in methanol. In situ protection of the amine products with di-tert-butyl dicarbonate eliminates functional group incompatibility of ester substrates and eliminates product inhibition in the reaction.
- Hansen, Karl B.,Rosner, Thorsten,Kubryk, Michele,Dormer, Peter G.,Armstrong III, Joseph D.
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p. 4935 - 4938
(2007/10/03)
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- Highly efficient synthesis of β-amino acid derivatives via asymmetric hydrogenation of unprotected enamines
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A direct asymmetric hydrogenation of unprotected enamino esters and amides is described. Catalyzed by Rh complexes with Josiphos-type chiral ligands, this method gives β-amino esters and amides in high yield and high ee (93-97% ee). No acyl protection/deprotection is required. Copyright
- Hsiao, Yi,Rivera, Nelo R.,Rosner, Thorsten,Krska, Shane W.,Njolito, Eugenia,Wang, Fang,Sun, Yongkui,Armstrong III, Joseph D.,Grabowski, Edward J. J.,Tillyer, Richard D.,Spindler, Felix,Malan, Christophe
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p. 9918 - 9919
(2007/10/03)
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- Substituted 3-phenyluracils
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A substituted 3-phenyluracil of the formula I where X1and X2are each oxygen; W is —C(R8)=X5, where X5is oxygen, sulfur, or a radical —NR14; R14is hydroxyl, alkoxy, alkenyloxy, al
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- Iron dichloride induced isomerization or reductive cleavage of isoxazoles: A facile synthesis of 2-carboxy-azirines
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5-Alkoxy-isoxazoles and N,N-disubstituted-5-isoxazolamines were found to isomerize to azirine derivatives by the use of iron dichloride as catalyst. On the contrary 5-alkyl- and 5-aryl-isoxazoles in the presence of the same salt, undergo reductive cleavage to enaminoketones. A common reaction intermediate is proposed.
- Auricchio, Sergio,Bini, Antonella,Pastormerlo, Eros,Truscello, Ada M.
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p. 10911 - 10920
(2007/10/03)
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