- Unusual Sensitivity to the Concentration of Ethanol in the Boron Trifluoride/Ethanol-Catalyzed Synthesis of 5,10,15,20-Tetrakis(4-cyano-2,6-dimethylphenyl)porphyrin by the Lindsey Method
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The boron trifluoride/ethanol-catalyzed condensation of 4-cyano-2,6-dimethylbenzaldehyde 1b with pyrrole by the Lindsey method to give the new, ortho-disubstituted 5,10,15,20-tetrakis(4-cyano-2,6dimethylphenyl)porphyrin 2 was found to be highly sensitive
- Steiger, Beat,Anson, Fred C.
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- Integration of an N-Heterocyclic Carbene Precursor into a Covalent Triazine Framework for Organocatalysis
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The successful incorporation of a thermally fragile imidazolium moiety into a covalent triazine framework resulted in a heterogeneous organocatalyst active in carbene-catalyzed umpolung reaction. The structural integrity of the imidazolium moiety was confirmed by combining solid-state NMR and XPS experiments.
- Troschke, Erik,Nguyen, Khoa Dang,Paasch, Silvia,Schmidt, Johannes,Nickerl, Georg,Senkovska, Irena,Brunner, Eike,Kaskel, Stefan
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supporting information
p. 18629 - 18633
(2018/11/25)
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- Regioselectivity of the ortho- and para-semidine, and diphenyline rearrangements
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The regioselectivity of the o-semidine, p-semidine, and diphenyline rearrangements of unsymmetrical N,N′-diarylhydrazines was studied experimentally. The results indicate that their electron-rich nitrogen atom is first protonated and then the electron-poor non-protonated nitrogen atom undergoes an N[1,3]-sigmatropic shift to the ortho-position of the electron-rich aryl rings, generating key intermediates. The intermediates can undergo (1) a direct proton transfer to give o-semidines, (2) a second N[1,3]-shift of the electron-poor nitrogen atom and then proton transfer to furnish p-semidines, and (3) a [3,3]-sigmatropic shift and subsequent proton transfer to yield diphenylines. It is the first N[1,3]-sigmatropic shift step that plays an important role in controlling the regioselectivity in the three rearrangements, further determining the structures of o-semidines, p-semidines, and diphenylines. The current results provide new insights into the o/p-semidine and diphenyline rearrangements and useful information for controlling and predicting the structures of the rearrangement products.
- Yang, Zhanhui,Hou, Shili,He, Wei,Cheng, Baoxiang,Jiao, Peng,Xu, Jiaxi
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p. 2186 - 2195
(2016/04/09)
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- A simple and practical preparation of an efficient water soluble olefin metathesis catalyst
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This study details homogeneous olefin metathesis in water catalysed by a di-ammonium functionalised Ru-alkylidene complex. A facile gram scale synthesis of an air stable catalyst precursor which can be readily converted to its water soluble derivative is described. The di-ammonium functionalised Ru-alkylidene complex facilitates a range of ring-closing metathesis (RCM) and cross-metathesis (CM) reactions in water.
- Wang, Zhen J.,Jackson, W. Roy,Robinson, Andrea J.
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supporting information
p. 3407 - 3414
(2015/06/25)
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- N[1,3]-sigmatropic shift in the benzidine rearrangement: Experimental and theoretical investigation
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The N[1,3]-sigmatropic shift in the benzidine rearrangement has been studied in depth experimentally with the aid of density functional theory (DFT) calculations. The designed substituted N,N′-diaryl hydrazines rearrange exclusively to the expected o/p-semidines and diphenylines. Intercrossing experiments support the intramolecular rearrangement process. Radical trapping experiments exclude the intermediacy of biradicals in the rearrangements. Computational results demonstrate that the o-semidine rearrangement involves a novel N[1,3]-sigmatropic shift and the p-semidine rearrangement proceeds via tandem N[1,3]/N[1,3]-sigmatropic shifts, while the diphenyline rearrangement occurs through cascade N[1,3]/[3,3]-sigmatropic shifts. The proposed mechanism involving the key N[1,3]-sigmatropic shift as the rate-limiting step is in good agreement with reported kinetic isotope measurements. The combined methods provide new insight into the formation mechanism of o/p-semidines and diphenylines in the benzidine rearrangement and support the unprecedented suprafacial symmetry allowed N[1,3]-sigmatropic shift with an inversion of the configuration in the migrating nitrogen atom. This journal is the Partner Organisations 2014.
- Hou, Shili,Li, Xinyao,Xu, Jiaxi
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supporting information
p. 4952 - 4963
(2014/07/07)
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- Mechanistic insight into the formal [1,3]-migration in the thermal claisen rearrangement
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The thermal formal [1,3]-sigmatropic shift of allyl aryl ethers has been studied in depth experimentally with the aid of the density functional theory (DFT) calculations of the B3LYP function. Three mechanistic possibilities, referred to as the radical, ionic, and concerted mechanisms, have previously been put forth to explain the thermal [1,3]-rearrangement process. However, the intercrossing and radical trapping experiments indicate the rearrangement is an intramolecular process. The computational studies reveal that the concerted C[1,3]-sigmatropic shift suffered from a higher energetic barrier to allow the rearrangement to proceed under the conditions used. However, a tandem O[1,3]-sigmatropic shift with a configuration inversion of the oxygen atom and [3,3]-sigmatropic shift (the Claisen rearrangement) is the most likely pathway for the formal [1,3] rearrangement. Furthermore, the rearrangement experiments with a designed optically active substrate and O[1,3]-sigmatropic shift examples verify the new cascade rearrangement. In addition, computational and experimental studies indicate that water molecule assists the proton shift during the isomerization. The combined methods provide the new insight into the mechanism of the thermal formal [1,3]-migration in the Claisen rearrangement and the novel O[1,3]-sigmatropic shift as well.
- Hou, Shili,Li, Xinyao,Xu, Jiaxi
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p. 10856 - 10869
(2013/02/23)
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- Increasing the scope of palladium-catalyzed cyanations of aryl chlorides
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An improved protocol for the palladium-catalyzed cyanation of electron-rich aryl chlorides with potassium ferrocyanide [K4[Fe(CN)6]] is presented. Compared to previous procedures the substrate scope is significantly broadened.
- Schareina, Thomas,Jackstell, Ralf,Schulz, Thomas,Zapf, Alexander,Cotte, Alain,Gotta, Matthias,Beller, Matthias
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experimental part
p. 643 - 648
(2009/11/30)
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- Non-nucleoside reverse transcriptase inhibitors
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The present invention provides for compounds useful for treating an HIV infection, or preventing an HIV infection, or treating AIDS or ARC. The compounds of the invention are of formula I wherein R1, R2, R3, R4, R5a, R5b, R6a, R6b and X are as herein defined. Also disclosed in the present invention are methods of treating an HIV infection with compounds defined herein and pharmaceutical compositions containing said compounds.
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Page/Page column 29; 30
(2008/12/06)
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- Novel thyroid hormone receptor antagonists with an N-alkylated diphenylamine skeleton
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Thyroid hormones play important roles in growth, development and homeostasis, and disruption of their functions induces serious disease, so novel synthetic thyroid hormone analogues are candidates for clinical application. We designed and synthesized nove
- Komatsu, Takuma,Hirano, Tomoya,Songkram, Chalermkiat,Kawachi, Emiko,Kagechika, Hiroyuki
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p. 3115 - 3126
(2008/02/04)
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- Aminoacetamide acyl guanidines as beta-secretase inhibitors
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There is provided a series of substituted acyl guanidines of Formula (Ik) or a stereoisomer; or a pharmaceutically acceptable salt thereof, wherein R2, R3, R4, R5, R25, R26 and R27 as defined herein, their pharmaceutical compositions and methods of use. These compounds inhibit the processing of amyloid precursor protein (APP) by β-secretase and, more specifically, inhibit the production of Aβ-peptide. The present disclosure is directed to compounds useful in the treatment of neurological disorders related to β-amyloid production, such as Alzheimer's disease and other conditions affected by anti-amyloid activity.
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Page/Page column 34
(2008/06/13)
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- HIV INHIBITING 2-( 4-CYANOPHENYLAMINO) PYRIMIDINE DERIVATIVES
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HIV replication inhibitors of formula (I) pharmaceut ically acceptable addition salts or stereochemically isomeric forms thereof, wherein X is NR4, S, SO or SO2; the preparation of these compounds as well as pharmaceutical compositio
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Page/Page column 20
(2008/06/13)
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