Protox inhibitors are applied as foliar sprays, thus causing very rapid cellular collapse and desiccation of many troublesome weeds in the presence of light. In many respects, they appear to be ideal herbicides, because they act rapidly and do not harm mammals under normal conditions. The main limitation to their widespread adoption is that few crops are naturally resistant to them. Crop tolerance has mainly been pursued with the synthesis of the cyclic imide classes containing 5- and 6-membered heterocycles, including pyrazole, pyridazine, 1,2,4-triazine, triazolinone and trifluoromethyluracil derivatives. Because of their structural novelties and biological performance, active investigations on heterocyclic protox inhibitors have been carried out in our laboratories and we have found 3-arylpyrroles to be a new class of light-activated, membrane-disrupting herbicides. They are active on both grass and broadleaf weeds at low rates. The synthesis and structure-activity relationships are presented.

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Trifluoromethyl‐substituted pyrazoles were synthesized via 1,3‐dipolar cycloaddition from sydnones 2a‐j and 1‐aryl‐3,3,3‐trifluoro‐propynes 5a‐f. The regioselectivity of the reaction and the spectroscopic characteristics of the products are discussed.

This paper reports the synthesis and the biological activity of benzoyl arylureas in which the aryl group bears a trifluoromethyl‐substitiited alkyl or alkenyl side chain, R. The activity of these compounds has been evaluated on larvae of S. littoralis, A. aegypti, L. decemlineata and on the eggs of T. urticae. In general: (1) the optimum insecticidal activities are achieved when the substituents on the benzoyl moiety, R1, and R2, are 2,6‐difluoro, the substituents on the aryl moiety, R3, are 3,5‐dichloro and R1, is 4‐(CHC(CI)CF3); (2) the best acaricidal activity is shown when R1, is 2‐CI, R2, and R3, are hydrogen atoms and R1, is 4‐(CH2CH2CH(CI)CF3); (3) the best overall activity is displayed when R1, is 2‐CI, R2 is hydrogen, R3 is 3‐chloro and R1 is 4‐(CH2CH2CF3).