- Contribution of Solvents to Geometrical Preference in the Z/ E Equilibrium of N-Phenylthioacetamide
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We studied the Z/E preference of N-phenylthioacetamide (thioacetanilide) derivatives in various solvents by means of 1H NMR spectroscopy, as well as molecular dynamics (MD) and other computational analyses. Our experimental results indicate that the Z/E isomer preference of secondary (NH)thioamides of N-phenylthioacetamides shows substantial solvent dependency, whereas the corresponding amides do not show solvent dependency of the Z/E isomer ratios. Detailed study of the solvent effects based on molecular dynamics simulations revealed that there are two main modes of hydrogen (H)-bond formation between solvent and (NH)thioacetamide, which influence the Z/E isomer preference of (NH)thioamides. DFT calculations of NH-thioamide in the presence of one or two explicit solvent molecules in the continuum solvent model can effectively mimic the solvation by multiple solvent molecules surrounding the thioamide in MD simulations and shed light on the precise nature of the interactions between thioamide and solvent. Orbital interaction analysis showed that, counterintuitively, the Z/E preference of NH-thioacetamides is mainly determined by steric repulsion, while that of sterically congested N-methylthioacetamides is mainly determined by thioamide conjugation.
- Chan, Erika S.,Hyodo, Tadashi,Ikeda, Hirotaka,Inagaki, Satoshi,Ohwada, Tomohiko,Otani, Yuko,Song, Shuyi,Tang, Yulan,Vu, Kim Anh L.,Yamaguchi, Kentaro
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- An efficient synthesis of benzothiazole using tetrabromomethane as a halogen bond donor catalyst
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An efficient and mild protocol has been developed for the synthesis of 2-substituted benzothiazole under solvent- and metal-free conditions using CBr4 as the catalyst. This process involves the activation of a thioamide through halogen bond formation between the sulphur atom of the thioamide and bromine atom of the CBr4 molecule. The presence of halogen-bonding interaction between N-methylthioamides and tetrabromomethane has been demonstrated with several control experiments, spectroscopic analysis and density functional theory (DFT). This methodology has a wide substrate scope for the synthesis of both 2-alkyl and 2-aryl substituted benzothiazoles.
- Kazi, Imran,Sekar, Govindasamy
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p. 9743 - 9756
(2019/12/02)
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- Iodoalkyne-Based Catalyst-Mediated Activation of Thioamides through Halogen Bonding
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Halogen bonding catalysis has recently gained increasing attention as a powerful tool to activate organic molecules. However, the variety of the catalyst structure has been quite limited so far. Herein, we report the first example of the use of an iodoalkyne as a halogen bond donor catalyst. By using an iodoalkyne bearing a pentafluorophenyl group as a catalyst, thioamides were efficiently activated and reacted with 2-aminophenol to generate benzoxazoles in good yield. Mechanistic studies, including 13C NMR spectroscopic analysis and several control experiments, provided concrete evidence that this catalytic activation is based on halogen bonding. Thus, the results obtained in this study demonstrate that iodoalkynes can serve as a new scaffold for future development of halogen bonding catalysis.
- Matsuzawa, Akinobu,Takeuchi, Shiho,Sugita, Kazuyuki
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supporting information
p. 2863 - 2866
(2016/10/25)
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- An efficient synthesis of a class of novel N-alkyl-N-aryl-4-hydroxy-1-methyl-2-oxo-1,2-dihydro-3- quinolinecarbothioamides
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The novel title compounds have been prepared in high yield by an optimized amide coupling followed by a Dieckmann cyclization. Additionally, this new route is amenable to preparative scale synthesis.
- Spears, Glen W.,Tsuji, Kiyoshi,Tojo, Takashi,Nishimura, Hiroaki,Ogino, Takashi
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p. 799 - 804
(2007/10/03)
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- DRUGS AUGMENTING NKT CELLS
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There is provided a NKT cell augmentation-mediated autoimmunosuppressant and/or potentiator on normal immune responses characterized by its comprising a compound of the following general formula or a pharmaceutically acceptable salt thereof as an active ingredient.[wherein R1 represents hydrogen or halogen,R2 represents hydroxy,R3 represents lower alkyl,R4 represents lower alkyl,R5 represents hydrogen or lower alkoxy, andZ represents O or S] Also provided is a novel process for synthesizing the above compound.
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- The first synthesis of N-alkyl-N-arylthiocarbamoylacetates and acetic acids
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N-Alkyl-N-arylthiocarbamoylacetates, the key intermediates for the synthesis of novel antinephritic agents, have been prepared for the first time. Some of the esters were in turn hydrolyzed to the corresponding acids. An alternative, indirect synthetic route was also developed to prepare some unusual acids.
- Spears, Glen W.,Tsuji, Kiyoshi,Tojo, Takashi,Nishimura, Hiroaki,Ogino, Takashi
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p. 565 - 574
(2007/10/03)
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- CYCLOADDITIONS TO KETENE-S,N-ACETALS. NEW SYNTHESES OF BENZO- AND NAPHTOFURANS, 1-BENZ- AND NAPHTHOZEPINS, AND BENZFURAN-2-ONES
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Annulation of ketene-S,N-acetal with 1,4-quinones gave benzo- and naphtofurans which were converted to 1-benz- and naphthoxepins and benzofuran-2-ones.
- Takahata, Hiroki,Anazawa, Akira,Moriyama, Keiko,Yamazaki, Takao
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- UNSATURATED THIOLATES AND THEIR ANALOGS IN CYCLOADDITION REACTIONS XI. EFFECT OF SUBSTITUENTS AT THE β POSITION OF ETHENETHIOLATES ON THE DIRECTION OF REACTION WITH CARBON BISULFIDE
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1-Dialkylamino-, 1-alkylarylamino-, and 1-cycloalkylaminoethenethiolates react with carbon bisulfide in various directions, depending on the nature of the substituents at the position 2.In all cases 1,2-dithiole-3-thiones are formed.Thiolates unsubstituted at position 2 give, in addition, 5,5'-bis(dialkylamino)-, 5,5'-bis(alkylarylamino)-, and 5,5'-bis(cycloalkylamine)-1,1',2,2'-tetrathiafulvalenes.In the case of potassium 1-morpholino-2-tert-butylethenethiolate the reaction is accompanied by the elimination of a molecule of morpholine and by the formation of 4-tert-butyl-1,2-dithiole-3-thione.In the presence of a weak proton donor (acetonitrile) ethylenethiolates substituted at position 2 react normally, but the 1-piperidinoethenethiolate gives mainly N,N-pentamethylenetrithiomalonamide.
- Bobylev, V. A.,Petrov, M. L.,Petrov, A. A.
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p. 239 - 245
(2007/10/02)
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- A convenient method for the selective reduction of amides to amines
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A variety of amides have been selectively reduced to the corresponding amines via conversion to their thioamides and treatment with triethyloxonium tetrafluoroborate followed by sodium borohydride. This procedure is compatible with isolated and conjugated double bonds, esters, intro groups, and sulfonamides.
- Raucher, Stanley,Klein, Peter
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p. 4061 - 4064
(2007/10/02)
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