Abstract Several substituted benzothiazoles were synthesized by the intramolecular cyclization of thioformanilides using 2, 6-dichloro-3, 5-dicyano-1, 4-benzoquinone (DDQ) in dichloromethane at ambient temperature in high yields. The resulting 2-arylbenzothiazoles were separated from the reduced DDQ byproduct 4, 5-dichloro-3, 6-dihydroxyphthalonitrile by treatment of the reaction mixture with a strongly basic ion-exchange resin. This protocol ...