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Paper | Regular issue | Vol 83, No. 8, 2011, pp.1819-1830
Published online, 24th June, 2011
DOI: 10.3987/COM-11-12247
Pyrido- and Quino-1,2,4-thiadiazine S,S-Dioxides from Reactions of 4-Chloro-3-pyridinesulfonyl- and 4-Chloro-3-quinolinesulfonyl Chlorides with O-Methylisourea

Elwira Chrobak, Michał Wlekliński, Andrzej Maślankiewicz,* Joachim Kusz, Maciej Zubko, and Ewa Michalik

*Department of Organic Chemistry, Medical University of Silesia, Jagiellońska 4, 41-200 Sosnowiec, Poland


Reaction of 4-chloro-3- pyridine- (or quinoline)sulfonyl chlorides (1) or (6) with O-methylisourea led to 4-chloro-3-pyridinesulfonyl-O-methylisourea (2a) or its quinoline analog 2b, respectively. Compounds 2a and 2b underwent dehydrochlorination to the title methoxy-pyrido or quino[4,3-e]-1,2,4-thiadiazine S,S-dioxides (3 and 7). X-Ray studies proved that both methoxy derivatives (3 and 7) exist as γazine-NH-tautomers. Reaction of N-H derivatives 3 and 7 with CH3I/CH3OK/DMF system proceeded at the pyridine-ring nitrogen and led to 7-methylpyrido derivative 4a or the 6-methylquino derivative 8a, respectively. After treatment with PhOP(O)Cl2 at 120-150 ºC compounds 4a or 8a were converted to chloro derivatives 4b or 8b, respectively, which were then transformed to aminothiadiazines 5a,b,c or 9a,b,c.