Cascade syntheses of aza[2,1-b][1,3]-benzothiazinone heteropolycyclic compounds from cyclic thiourea catalyzed by Cu(I)

An efficient cascade method has been developed for the synthesis of aza[2,1-b][1,3]-benzothiazinones from cyclic thiourea and methyl 2-iodobenzoate via the Cu(I)-catalyzed C–S coupling/amidation process. A number of aza[2,1-b][1,3]-benzothiazinones containing five, six, seven membered rings and different substituents were obtained in good yield.