Synthesis of 2,5-diamino-oxazole (2a), 2,5-diamino-thiazole (2b), 2,4-diamino-5H-imidazole (3) derivatives were achieved through reactions of chloroacetanilide (1) with urea, thiourea and guanidine, respectively. Compounds 5a, b were also prepared. Compound 6 was obtained upon heating of 5a with acetic anhydride in presence of acetic acid. We have used the ANRORC approach to obtain compounds 7a, b and 8. Reactions of arylidene-malononitriles or (z)-ethyl-2- cyano-3-arylacrylates with 8 gave compounds 9a-c and 10a-c. Compounds 11a-c was obtained via cyclization of 8 with aldehyde and thiourea. Biological studies were undertaken to asses the effect of some these new compounds on altered biochemical parameters in deltamethrin-exposed rats. Blood cholinesterase activity was significantly inhibited, 25% and 15% for plasma and erythrocyte, after rat treatment with deltamethrin for one month.