Synthesis and anthelminthic evaluation of 2-amidino-1,3,4-oxa and 1,3,4-thiadiazoles, structurally related to tetramisole.

N-(1,3,4-thiadiazol-2-yl) 1a-1k and N-(1,3,4-oxadiazol-2-yl-) amidines 2a-2g, N-(1,3-thiazol-2-yl) 3a, 3b and N-(1,3-benzothiazol-2-yl-)amidines 4a, 4b were synthesized and tested as anthelminthics, in vitro, against a free nematode (Rhabditis pseudoelongata), against infecting larvae of an intestinal parasite of rats (Nippostrongylus brasiliensis) and against infecting larvae of a filaria (Molinema dessetae).