Isothiourea derivatives of 6-phenyl-2,3,5,6-tetrahydroimidazo[2,1-b]thiazole with broad-spectrum anthelmintic activity

A series of isothiourea derivatives of 6-phenyl-2,3,5,6-tetrahydroimidazo[2,1-b]thiazole (tetramisole) is described. The compounds are prepared by the S-alkylation of the thioureas that were obtained either by the reaction of an amine with 6-(3-isothiocyanatophenyl)-2,3,5,6-tetrahydroimidazo[2,1-b] thiazole or by the reaction of an isothiocyanate with 6-(3-aminophenyl)-2,3,5,6-tetrahydroimidazo[2,1-b]thiazole. These derivatives have an improved spectrum of activity over tetramisole and are active against nematodes, cestodes, and trematodes. The structure-activity relationships are discussed.