Synthesis and molluscicidal evaluation of some new pyrazole, isoxazole, pyridine, pyrimidine, 1,4-thiazine and 1,3,4-thiadiazine derivatives incorporating benzofuran moiety.

Chalcone derivative 3 was synthesized via the base catalyzed Claisen-Schmidt condensation and was used as a precursor for synthesizing pyrazoline 11, isoxazoline 12, pyrazoline carbothioamide 13, 5,6-dihydropyrimidine-2-(1H)-thione 14 and aminopyridinecarbonitrile derivative 15. Bromination of 3 afforded the dibromo derivative 4. Monobromo derivative 5 obtained by boiling 4 in dry benzene in the presence of triethylamine. Fused thiadiazines 9a,b and 1,4-thiazine 9c derivatives were synthesized upon treatment of α-bromopropenone derivative 5 with 4-amino-4H-1,2,4-triazole-3-thiol (6) or 1-amino-2-mercapto-5-methylpyrimidin-4(1H)-one (7) or with 2-aminothiophenol (8) in ethanolic potassium hydroxide solution. The newly synthesized compounds were screened for their molluscicidal activities, whereas compounds 3, 4, 9a, 11 and 15 exhibited promising molluscicidal activities. On the other hand compounds 5, 9b, 9c, 12, 13 and 14 showed a moderate effect as compared to the standard molluscicidal agent (Bayluscide).

Oxazole, pyrazole and piperidine derivatives having an o-hydroxyaryl moiety with anticipated molluscicidal activity.

The condensation reactions of hippuric acid and its furyl derivative with salicylaldehydes or that of salicylhippuric acid analogues with furaldehyde led to the corresponding oxazoles. These were subsequently treated with hydrazine hydrate, hydroxylamine or subjected to alkaline hydrolysis to yield new o-hydroxyaryl or salicyl containing derivatives. 5-Substituted salicylanilides were treated with piperidine and formaldehyde in a Mannich type reaction affording the corresponding 3-(N-piperidinomethyl) salicylanilides. It was noticed that the presence of an electron donating group in position 3 in the salicylanilide moiety decreases the molluscicidal activity.