Benzo </ -1,2-thiazole-1,1 -dioxides

N,N-Diacyl-thiohydroxylamine werden durch Natrium-bis-[2-methoxy-athyl]-dihydrido-aluminat in Benzol mit guten Ausbeuten zu Aldehyden reduziert. Mit Hilfe von 3-Oxo-2,3-dihydro-(benzo-[d]-l,2-thiazol)-l,l-dioxid gelingt es auf diese Weise Car-bonsaure-chloride auf einfache Weise in Aldehyde zu iiberfiihren z. B.2 ... 

J 4-Hydroxy-2-methyl-1,1-dioxo-1,2-di hydro-116-benzo[e][1,2]thiazine-3-carboxylic acid (5-methyl-thiazol-2-yl)-amide, 4-hydroxy-2-methyl-A/-(5-methyl-2-thiazoyl)-2H-1,2-benzothiazine-3-carboxamide-1,1 -dioxide, C14H13N3O4S2, Mr 351.40, mp 264 °C (decomp.)... 

A novel synthesis of 7-substituted benzo[d]-l,2-thiazole-l,1-dioxides (22) has been described and involves direct lithiation of the pivalamides (21). Subsequent cyclisation and finally, incorporation of an electrophile into the 7-position gives (22)... 

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