- Single-step microwave-mediated synthesis of oxazoles and thiazoles from 3-oxetanone: A synthetic and computational study
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The direct microwave-mediated condensation between 3-oxetanone and primary amides and thioamides has delivered moderate to good yields of (hydroxymethyl)oxazoles and (hydroxymethyl)thiazoles. The reactions use a sustainable solvent and only require short reaction times. These are highly competitive methods for the construction of two classes of valuable heteroarenes, which bear a useful locus for further elaboration. Electronic structure calculations have shown that the order of events involves chalcogen atom attack at sp3 carbon and alkyl-oxygen cleavage. The critical role of acid catalysis was shown clearly, and the importance of acid strength was demonstrated. The calculated barriers were also fully consistent with the observed order of thioamide and amide reactivity. Spontaneous ring opening involves a modest degree of C-O cleavage, moderating the extent of strain relief. On the acid-catalysed pathway, C-O cleavage is less extensive still, but proton transfer to the nucleofuge is well advanced with the carboxylic acid catalysts, and essentially complete with methanesulfonic acid. Open sesame: The direct microwave-mediated condensation between 3-oxetanone and primary amides and thioamides has delivered moderate to good yields of oxazoles and thiazoles. The reactions use a sustainable solvent, require only short reaction times and represent a highly competitive method for the construction of two classes of valuable heteroarenes. Electronic structure calculations have been used to probe a range of potential reaction mechanisms (see figure). Copyright
- Orr, David,Tolfrey, Alexandra,Percy, Jonathan M.,Frieman, Joanna,Harrison, Zo? A.,Campbell-Crawford, Matthew,Patel, Vipulkumar K.
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supporting information
p. 9655 - 9662
(2013/07/26)
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- Synthesis and in-vitro cytotoxicity of poly-functionalized 4-(2-arylthiazol-4-yl)-4H-chromenes
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A new series of 4-aryl-4H-chromenes bearing a 2-arylthiazol-4-yl moiety at the 4-position were prepared as potential cytotoxic agents. The in-vitro cytotoxic activity of the synthesized 4-aryl-4H-chromenes was investigated in comparison with etoposide, a well-known anticancer drug, using MTT colorimetric assay. Among them, the 2-(2-chlorophenyl)thiazol-4-yl analog 4b showed the most potent activity against nasopharyngeal epidermoid carcinoma KB, medulloblastoma DAOY, and astrocytoma 1321N1, and compound 4d bearing a 2-(4-chlorophenyl) thiazol-4-yl moiety at the 4-position of the chromene ring exhibited the best inhibitory activity against breast cancer cells MCF-7, lung cancer cells A549, and colon adenocarcinoma cells SW480 with IC50 values less than 5 μM. The ability of compound 4b to induce apoptosis was confirmed in a nuclear morphological assay by DAPI staining in the KB and MCF-7 cells.
- Mahmoodi, Majid,Aliabadi, Alireza,Emami, Saeed,Safavi, Maliheh,Rajabalian, Saeed,Mohagheghi, Mohammad-Ali,Khoshzaban, Ahad,Samzadeh-Kermani, Alireza,Lamei, Navid,Shafiee, Abbas,Foroumadi, Alireza
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p. 411 - 416
(2011/08/05)
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- Synthesis of new 1,4-dihydropyridine derivatives containing thiazolyl substituents
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A series of 4-[2-methyl (or aryl) thiazole-4-yl]-2,6-dimethyl-3,5-diacetyl (or dibenzoyl) 1,4-dihydropyridines were synthesized using a modified Hantzsch reaction involving the condensation of the corresponding aldehyde with acetyl acetone or benzoyl acetone. The preparation of the corresponding aldehydes (2-methylthiazole-4-carboxaldehyde and some 2-arylthiazole-4-carboxaldehydes) was achieved by a simplified protocol of the published synthesis.
- Bazargan, Leila,Shafiee, Abbas,Amini, Mohsen,Dezfouli, Ebrahim Bakhshi,Azizi, Ebrahim,Ghaffari, Seyed Mahmood
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scheme or table
p. 602 - 609
(2009/10/02)
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- INHIBITORS OF HCV NS5B POLYMERASE
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The present invention porivdes compounds of Formula I, compositons and methods that are useful for treating viral infections and associated diseases, particularly HCV infections and associated diseases.
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