Antileukemic activity of substituted ureidothiazoles, ureidothiadiazoles, and related compounds.

A number of ureidothiazole and ureidothiadiazole derivatives related to ethyl 4-[[(2-thiazolylamino)carbonyl]-amino]benzoate were prepared and evaluated against the leukemia P-388 tumor system in mice. Preliminary structure-activity relationship study revealed that, among other considerations, active compounds of this series contain either an "isothioureido" [N-C(S-)=N-] or an "isothiosemicarbazono" [N-C(S-)=N-N=] structural unit.