Chemistry of phosphorous ylides 16 the insecticidal and molluscidal activity of new organophosphorus compounds

ABSTRACT

The activity of some new organophosphorous compounds against the Egyptian cotton leafworm Spodoptera littoralis and the fresh water snail Biomphalaria alexandrina was studied. These compounds were prepared from the reaction of active [Aa, b], stabilized phosphonium ylides [Ba-e, C] or iminophosphorane [D] with alpha, beta-unsaturated carbonyl compounds [1, 10, 20]. Eighteen compounds were prepared, phosphoranylidene pyranones [2, 11], thioxophosphoranylidene pyranones [12, 21], complex phosphoranes [3-7, 13-17], oxaphosphorins [8, 18] and oxazaphosphorins [9, 19]. Only four chemical structures from these organophosphorous reagents and the alpha, beta-unsaturated organic compound were found to be active and showed satisfactory results as insecticides. The stomach action of these structures, however, was higher than the contact one. On the other hand, the molluscicidal toxicity was more pronounced, where 8 out of 21 structures displayed good effects in this respect. Although the toxicity of the prepared compounds are varied greatly according to their structures and the test organism, they are still less active than the commercially available pesticides