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Paper | Regular issue | Vol 91, No. 11, 2015, pp.2097-2112
Published online, 23rd October, 2015
DOI: 10.3987/COM-15-13309
Synthesis and Transformations of 2-Oxo-2,3-dihydro-(1H,3H)-quino[4,3-e]-1,2,4-thiadiazine 4,4-Dioxide to N-Methyl-, 2-Chloro- and 2-Aminoquino[4,3-e]-1,2,4-thiadiazine 4,4-Dioxides

Elwira Chrobak,* Stanisław Boryczka, Michał Wlekliński, Joachim Kusz, Maciej Zubko, and Andrzej Maślankiewicz

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

Abstract

Fusion of 4-amino-3-quinolinesulfonamide (1a) with urea and N-methyl- and N,N’-dimethylurea resulted in 2-oxo-2,3-dihydro-(1H,3H)- quino[4,3-e]-1,2,4-thiadiazine 4,4-oxide (3a). Reaction of thiadiazinone 3a with a MeI/MeOK/DMF system gave a mixture of the 3-methyl derivative 3c (major product) and 6-methyl derivative 3d (minor product), and the mixture of 3c and 3d could be methylated with the same system as above to afford the 3,6-dimethyl derivative 3e. Chlorination of 3a with P(O)Cl3/phosphoric acid system performed in the presence of pyridine hydrochloride resulted in zwitterionic pyridinio-quinothiadiazinate 7 (63%) accompanied by 2-chloroquinothiadiazine 6 (15%), and the same reaction performed with the use of triethylamine hydrochloride gave the expected chloroquinothiadiazine 6 (73%). Chloro derivative 6 was then aminated to 2-aminoquinothiadiazines 8a,b,c.