- Synthesis of coumarin substituted triazolothiadiazine derivatives via ring transformation reaction
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A novel ring transformation reaction for the synthesis of 3-(3-aryl-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-6-yl)-2H-chromen-2-ones has been described. Reaction of 3-(2-bromoacetyl)coumarins (1) with 5-aryl-1,3,4-oxadiazole-2-thiol (2) gave ketones (4a-h). The in situ formed ketones (4a-h) were reacted with hydrazine hydrate to give 3-(3-aryl-7H-[1,2,4] triazolo[3,4-b][1,3,4]thiadiazin-6-yl)-2H-chromen-2-ones (3a-h) and not 5 or 6. The compounds (3a-h) can also be prepared by the reaction of 3-(2-bromoacetyl)coumarins (1) with 5-aryl-1,3,4-oxadiazole-2-thiol (2) in anhydrous ethanol to give corresponding 3-(2-(5-aryl-1,3,4-oxadiazol-2-ylthio) acetyl)-2H-chromen-2-ones (4a-h). These on reaction with hydrazine hydrate in acetic acid gave corresponding 3-(3-aryl-7H-[1,2,4]triazolo[3,4-b][1,3,4] thiadiazin-6-yl)-2H-chromen-2-ones (3a-h).
- Chunduru, Venkata Sreenivasa Rao,Rajeswar Rao, Vedula
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p. 159 - 163
(2013/04/10)
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- Synthesis and antioxidant evaluation of some new 3-substituted coumarins
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3-Acetylcoumarin (1) was utilized as a key intermediate for the synthesis of 2-aminothiazole derivative 3 via bromination of 1 to afford acetylbromide 2 followed by treatment with thiourea or via Biginelli reaction of 1. Treatment of 3 with 5-chloro-3-met
- Hamama, Wafaa S.,Berghot, Moged A.,Baz, Eman A.,Gouda, Moustafa A.
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p. 710 - 718
(2012/07/13)
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- A simple and efficient synthesis of 3-(3-phenyl-7H-[1,2,4]triazole[3,4][1, 3,4]thiadiazin-6-yl)chromen-2-ones
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The compounds 3-(3-phenyl-7H-[l,2,4]triazole[3,4][l,3,4]thiadiazin-6-yl) chromen-2-ones (3), have been prepared by the condensation of 3-(2-bromoacetyl)chromen-2-ones (1) with 4-amino-5-phenyl-4H[l,2,4]triazole-3- thiols (2), under reflux in ethanol. A si
- Tasqeeruddin,Dubey
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experimental part
p. 3744 - 3746
(2012/01/12)
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- A NOVEL SYNTHESIS OF THIAZOLYL, IMIDAZOTHIADIAZOLYL, AND THIADIAZINYL-2H-1-BENZOPYRAN-2-ONES
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3-Acetylcoumarins I with arylthiourea in the presence of iodine gave substituted-3-(2-arylamino-4-thiazolyl)-2H-1-benzopyran-2-ones (IIa-IIc.) The structures of these products have been confirmed and they were converted into acetyl derivatives (IId-IIf.)
- Rao, V. Rajeswar,Rao, M. S.,Rao, T. V. Padmanabha
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p. 2214 - 2221
(2007/10/02)
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