- Generation and Reactivity of Electron-Rich Carbenes on the Surface of Catalytic Gold Nanoparticles
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The reactive nature of carbenes can be modulated, and ultimately reversed, by receiving additional electron density from a metal. Here, it is shown that Au nanoparticles (NPs) generate an electron-rich carbene on surface after transferring electron density to the carbonyl group of an in situ activated diazoacetate, as assessed by Fourier transformed infrared (FT-IR) spectroscopy, magic angle spinning nuclear magnetic resonance (MAS NMR), and Raman spectroscopy. Density functional theory (DFT) calculations support the observed experimental values and unveil the participation of at least three different Au atoms during carbene stabilization. The surface stabilized carbene shows an extraordinary stability against nucleophiles and reacts with electrophiles to give new products. These findings showcase the ability of catalytic Au NPs to inject electron density in energetically high but symmetrically allowed valence orbitals of sluggish molecules.
- Oliver-Meseguer, Judit,Boronat, Mercedes,Vidal-Moya, Alejandro,Concepción, Patricia,Rivero-Crespo, Miguel ángel,Leyva-Pérez, Antonio,Corma, Avelino
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- Vinyl esters as effective acetaldehyde surrogates in [4 + 1] cycloaddition based multicomponent cascade
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A new multicomponent cascade has been designed by utilizing vinyl esters as effective acetaldehyde surrogate. While most of the cyclic α-ketoenols underwent a facile three component conversion to annulated furans, phenols such as naphthol and sesamol got
- Kumar, Manoj,Bagchi, Sourav,Sharma, Anuj
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- Selective synthesis of spiro and dispiro compounds using Mn(III)-based oxidation of tetracarbonyl compounds
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The Mn(III)-based oxidation of methylenebis(cyclohexanedione)s and methylenebis(piperidinedione)s as a tetracarbonyl compound was investigated under various conditions, selectively producing spiro dihydrofurans and dispiro cyclopropanes depending on the solvent. The mechanism for the formation of the spiro dihydrofurans and dispiro cyclopropanes was discussed. In addition, a simple synthesis of a new type of alkaloid, 3,4,6,7,8,10-hexahydro-1H-pyrano[3,2-c:5,6-c’]dipyridine-1,9(2H)-diones, was demonstrated.
- Hisano, Kazuki,Nishikawa, Satomi,Nishino, Hiroshi,Shibuya, Keisuke,Yokote, Suzuka
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supporting information
(2020/04/21)
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- Regio- and enantioselective reduction of diketones: Preparation of enantiomerically pure hydroxy ketones catalysed by Candida parapsilosis ATCC 7330
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Enantiomerically enriched hydroxy ketones were prepared by the reduction of the corresponding diketones with excellent enantiomeric excess (98%) and in good yields (up to 75%) using whole cells of Candida parapsilosis ATCC 7330. Cyclic diketones, such as 1,2-cyclohexanedione and 1,4-cyclohexanedione, resulted in hydroxy ketones as products. Cyclohexane-1,3-dione and 5,5-dimethylcyclohexane-1,3-dione gave dimerised products, such as 2,2′-(ethane-1,1-diyl)bis(3-hydroxycyclohex-2-enone) and 2,2′-(ethane-1,1-diyl)bis(3-hydroxy-5,5-dimethylcyclohex-2-enone) with acetaldehyde generated in situ from whole cells of Candida parapsilosis ATCC 7330, which is reported here for the first time.
- Mahajabeen, Pula,Chadha, Anju
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p. 1167 - 1173
(2015/10/28)
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- Reaction of aldehydes and 5,5-dimethyl-1,3-cyclohexanedione in the presence of surfactants in water
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An efficient and convenient approach to the synthesis of the two different products from aldehydes and 5,5-dimethyl-1,3-cyclohexanedione using two kinds of surfactant catalysts sodium dodecyl sulfate (SDS) and dodecanesulfonic acid (DSA) (10 mol %) is des
- Qin, Xin-Ying,Jin, Tong-Shou,Zhang, Jian-She,Li, Tong-Shuang
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experimental part
p. 1173 - 1178
(2012/03/11)
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- Organocatalytic sequential one-pot double cascade asymmetric synthesis of Wieland-Miescher ketone analogues from a knoevenagel/hydrogenation/robinson annulation sequence: Scope and applications of organocatalytic biomimetic reductions
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(Chemical Equation Presented) A practical and novel organocatalytic chemo- and enantioselective process for the cascade synthesis of highly substituted 2-alkyl-cyclohexane-1,3-diones and Wieland-Miescher (W-M) ketone analogs is presented via reductive alk
- Ramachary, Dhevalapally B.,Kishor, Mamillapalli
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p. 5056 - 5068
(2008/02/08)
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- Solid-state condensation reactions between aldehydes and 5,5-dimethyl-1,3-cyclohexanedione by grinding at room temperature
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An efficient and convenient approach to the synthesis of the two different products from aldehydes and 5,5-dimethyl-1,3-cyclohexanedione in the solid state by grinding is described. This method provides several advantages such as environmental friendlines
- Jin, Tong-Shou,Zhang, Jian-She,Wang, Ai-Qing,Li, Tong-Shuang
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p. 2339 - 2345
(2007/10/03)
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- A synthetic entry into fused pyran derivatives through carbon transfer reactions of 1,3-oxazinanes and oxazolidines with carbon nucleophiles
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Acid catalysed condensations of various 2 substituted 1,3-oxazinanes 3 and 1,3-oxazolidines 4 with cyclic carbon nucleophiles viz. 5,5-dimethyl-1,3-cyclohexanedione and 1,3-cyclohexanedione furnish xanthene derivatives, whereas a Knoevenagel reaction proceeds with acyclic nucleophiles. In case of 4b and 4c, a unique synthesis of functionalised α-tetralones has emerged. Reactions of mixtures of cyclic and acyclic carbon nucleophiles with 3 provide some functionalised and partially reduced benzopyran derivatives.
- Singh, Kamaljit,Singh, Jasbir,Singh, Harjit
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p. 14273 - 14280
(2007/10/03)
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