Abstract: | The general reaction of intramolecular nucleophilic substitution of unactivated aryl groups by thioamide anion in dipolar aprotic amide solvent is extended by the syntheses of 6-chloro-5-methoxy-2-methylbenzothiazole from 2′,4′-dichloro-5′-methoxythioacetanilide and 6-methoxy-2-methylbenzothiazole from 4′-methoxy-2′-nitrothioacetanilide. The six-membered fused ring heterocycles, 2-methyl-4H,3-benzothiazine and 6,8-dichloro-3-rnethyl-1H-4,1,2-benzothiadi-azine are also prepared. |