A convenient synthesis of novel 1,3-phenylene bridgedbis-heterocyclic compounds

Reactions of bis-hydrazonoyl bromide 1 with each of phenyl-5-arylidene-2-thioxo-thiazol-4-one, triazinethiones and 4,6-dimethyl-2,6-dioxocyclohexane-1-thiocarboxanilide as sulfur dipolarophilic reagents led to the formation of the hitherto unreported 1,3-phenylene bis-heterocycles 4, 8 and 10, respectively. The structures of the isolated products were established on the basis of their elemental and spectral analyses. The mechanism and the site selectivity in the studied reactions are discussed.