- Photoswitchable elements within a peptide backbone-ultrafast spectroscopy of thioxylated amides
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A series of thioxo compounds, thioacetamide, N-methylthioacetamide, a cyclic thioxoamide [(S)-5-thioxopyrrolidine-2-carboxylic acid ethyl ester], two thioxylated dipeptides (Ala-Ψ[CS-NH]-Ala and Phe-Ψ[CS-NH]-Ala) and a thioxylated dodecapeptide (Lys-Glu-Thr-Ala-Ala-Ala-Lys-Phe-Glu-Arg-Gln-His- Ψ[CS-NH]-Nle-Asp-Ser-Ser-Thr-Ser-Ala-Ala, or [thioxo-His12]-S- peptide; Nle = norleucine) are investigated by ultrafast spectroscopy in the visible and near UV. The different molecules show very similar absorption dynamics featuring a rise of a strong visible absorption band on the subpicosecond and picosecond time scale. The decay of the visible absorption occurs within 150-600 ps. The observations are interpreted by the ultrafast formation of triplet states and their decay on the subnanosecond time scale. Comparison with published ER experiments on N-methylthioacetamide indicates that the cis-trans isomerization around the thioxopeptide bond is terminated within less than 1 ns.
- Satzger,Root,Gilch,Zinth,Wildemann,Fischer
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Read Online
- 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.
- Song, Shuyi,Hyodo, Tadashi,Ikeda, Hirotaka,Vu, Kim Anh L.,Tang, Yulan,Chan, Erika S.,Otani, Yuko,Inagaki, Satoshi,Yamaguchi, Kentaro,Ohwada, Tomohiko
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p. 1641 - 1660
(2021/06/28)
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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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- Facile synthesis of thioamides via P2S5-mediated beckmann rearrangement of oximes
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A facile and efficient approach to the synthesis of secondary thioamides from ketoximes via Beckmann rearrangement has been established, using phosphorus pentasulfide as a dehydrating and thiating agent. It is also efficient for the preparation of primary thiobenzamide from benzaldoxime. This approach features simple-operation, easy-control and good to excellent yields.
- Li, Jiangsheng,Cheng, Chao,Zhang, Xinrui,Li, Zhiwei,Cai, Feifei,Xue, Yuan,Liu, Weidong
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p. 1687 - 1689
(2012/10/29)
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- Facile and odorless one-pot process for the synthesis of N-substituted thioamides via TsCl-mediated Beckmann rearrangement of ketoximes
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A facile and odorless one-pot thionation process for the synthesis of N-substituted thioamides using chemically stable and inexpensive thiourea reagent via the Beckmann rearrangement of ketoximes, has been described. Georg Thieme Verlag Stuttgart · New York.
- Liu, Li-Feng,An, Na,Pi, Hong-Jun,Ying, Jun,Du, Wenting,Deng, Wei-Ping
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supporting information; experimental part
p. 979 - 981
(2011/06/11)
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- NOVEL PHENYL IMIDAZOLES AND PHENYL TRIAZOLES AS GAMMA-SECRETASE MODULATORS
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Compounds and pharmaceutically acceptable salts of the compounds are disclosed, wherein the compounds have the structure of Formula (I) as defined in the specification. Corresponding pharmaceutical compositions, methods of treatment, methods of synthesis, and intermediates are also disclosed
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Page/Page column 48
(2010/09/18)
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- Ketoximes to N-substituted thioamides via PSCl3 mediated Beckmann rearrangement
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N-Substituted thioamides were accessed from ketoximes by utilising PSCl3 as a uniquely capable reagent to induce Beckmann rearrangement as well as to capture the intermediate nitrilium ion. The Royal Society of Chemistry 2009.
- Pathak, Uma,Pandey, Lokesh Kumar,Mathur, Sweta,Suryanarayana
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scheme or table
p. 5409 - 5411
(2009/12/08)
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- Dichlorothiophosphoric acid and dichlorothiophosphate anion as thionating agents in the synthesis of thioamides
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A method for the thionation of carboxylic acid amides with dichlorothiophosphoric acid and dichlorothiophosphate anion, providing thioamides in high yields, was developed. The facility of the thionation and the yields of the final products were shown to depend on the nature of the starting amide. The optimal reaction conditions are reported.
- Bezgubenko,Pipko,Sinitsa
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experimental part
p. 1341 - 1344
(2009/02/07)
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- A Facile Conversion of Amides and Lactams to Thioamides and Thiolactams using Tetrathiomolybdate
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Chloro iminium salts generated in situ from amides and lactams using (COCl)2 or POCl3 reacted very readily with the new sulfur transfer reagent, benzyltriethylammonium tetrathiomolybdate to afford the corresponding thioamides and thiolactams in excellent yields under mild reaction conditions.
- Ilankumaran, Palanichamy,Ramesha, A. R.,Chandrasekaran, Srinivasan
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p. 8311 - 8314
(2007/10/02)
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- Conversion of Amides and Lactams to Thioamides and Thiolactams Using Hexamethyldisilathiane
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Amides and lactams were converted to their corresponding thioamides and thiolactams employing a new protocol using hexamethyldisilathiane (TMS2S).Oxophilic promoters were employed to generate Vilsmeier-type intermediates, the most efficient reagents being phosphorus oxychloride, triphosgene, and oxalyl chloride.Thionation of intermediate chloro iminium ions was accomplished in situ with TMS2S.Yields were good to excellent for secondary and tertiary amides and lactams while yields for primary systems were poor.
- Smith, D. C.,Lee, S. W.,Fuchs, P. L.
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p. 348 - 354
(2007/10/02)
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- A New Route to N-Monosubstituted Thioamides Utilizing Phosphoramidothionates as Reagents for the Thioamidation of Carboxylic Acids
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Several N-monosubstituted thioamides have been synthesized from the corresponding carboxylic acid chlorides and primary amines by a new procedure.The procedure utilizes a commercially available and inexpensive organophosphorus reagent (dimethyl chlorothiophosphate) to derivatize the amine, form the carboxamide bond, and accomplish the thionation of the carbonyl by an intramolecular rearrangement.The phosphoryl group is then cleaved from the resulting thiocarbonyl phosphoryl mixed imide by a simple hydrolysis.Thioamides (RCSNHR') containing a variety of functionality(R= simple alkyl, phenyl, bulky alkyl, cycloalkylalkyl, α,β-unsaturated, and alkyl with remote keto, ester, or amide carbonyl groups; R'= methyl, benzyl, allyl) have been prepared by this method in generally high overall yields (50-80 percent).Competing thionation of remote carbonyl groups or epimerization of a chiral center containing a proton α to a ketone group was not observed.
- DeBruin, Kenneth E.,Boros, Eric E.
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p. 6091 - 6098
(2007/10/02)
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