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Molecules 2012, 17(6), 6930-6943; doi:10.3390/molecules17066930
Article

Bromination and Diazo-Coupling of Pyridinethiones; Microwave Assisted Synthesis of Isothiazolopyridine, Pyridothiazine and Pyridothiazepines

1, 2,† and 3,‡,*
1 Department of Chemistry, Faculty of Science, Fayoum University, Fayoum 63514, Egypt 2 Department of Chemistry, Faculty of Science, El-Jabal El-Gharby University, Mezda, Gheryan 65096, Libya 3 Department of Chemistry, Faculty of Science, Taif University, Taif 21974, Saudi Arabia Current address: Department of Chemistry, Faculty of Science, Ain-Shams University, Cairo 11566, Egypt. Current address: Department of Chemistry, Faculty of Science, Cairo University, Cairo 12613, Egypt.
* Author to whom correspondence should be addressed.
Received: 25 April 2012 / Revised: 23 May 2012 / Accepted: 31 May 2012 / Published: 6 June 2012
(This article belongs to the Section Organic Synthesis)
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Abstract

Isothiazolopyridines, pyridothiazines and pyridothiazepines are important compounds that possess valuable biological activities. This paper reports on the synthesis of these compounds using both conventional chemical methods and modern microwave techniques. 3-Bromo-6-hydroxy-4-methyl-2-thioxo-2,3-dihydropyridine-3-carboxamide, 5-arylazo-6-hydroxy-4-methyl-2-thioxo-1,2-dihydropyridine-3-carboxamides, 3,5-bis-arylazo-6-hydroxy-4-methyl-2-thioxo-2,3-dihydropyridine-3-caboxamide, 4-methyl-2,3,6,7-tetra-hydroisothiazolo[5,4-b]-pyridine-3,6-dione, 2,2'-(methylene-bis-(sulfanediyl))bis(4-methyl-6-oxo-1,6-dihydropyridine-3-carboxamide), 2-hydroxy-5-methyl-4H-pyrido[3,2-e][1,3]-thiazine-4,7(8H)-dione and 2-arylmethylene-8-hydroxy-6-methyl-2,3,4,5-tetrahydropyrido-[3,2-f][1,4]thiazepine-3,5-diones have been prepared from 6-hydroxy-4-methyl-2-thioxo-2,3-dihydropyridine-3-carboxamide. Some of these compounds were prepared using microwave-assisted reaction conditions, that provided higher yields in shorter times than the conventional methods.
Keywords: microwave; bromination; diazo-coupling; pyridinecarboxamide; isothiazolopyridine; pyridothiazine; pyridothiazepine microwave; bromination; diazo-coupling; pyridinecarboxamide; isothiazolopyridine; pyridothiazine; pyridothiazepine
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Youssef, A.M.S.; Azab, M.E.; Youssef, M.M. Bromination and Diazo-Coupling of Pyridinethiones; Microwave Assisted Synthesis of Isothiazolopyridine, Pyridothiazine and Pyridothiazepines. Molecules 2012, 17, 6930-6943.

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