Organic syntheses based on 2-oxoglutaric acid .5. Syntheses of novel 2H-1,4-benzothiazines and a 2,5-dihydro-1,5-benzothiazepine

Syntheses aimed on the incorporation in heterocycles of segments originating in the precursor 2-oxoglutaric acid are described. Cylocondensation of dimethyl 2-oxoglutarate 1, dimethyl 3-bromo-2-oxoglutarate 2, and dimethyl (E)-2-oxoglutaconate 3 with 2-aminobenzenethiol gave rise to the novel 2H-1,4-benzothiazines 4 and 5, and the 2,5-dihydro-1,5-benzothiazepine 6, respectively, by incorporation of either the segments C-1/C-2 or C-2/C-3 or C-3/C-4/C-5 of the precursor.