Kristy Bryan

The discovery of Arylex™ active and Rinskor™ active: Two novel auxin herbicides.

Multiple classes of commercially important auxin herbicides have been discovered since the 1940s including the aryloxyacetates (2,4-D, MCPA, dichlorprop, mecoprop, triclopyr, and fluroxypyr), the benzoates (dicamba), the quinoline-2-carboxylates (quinclorac and quinmerac), the pyrimidine-4-carboxylates (aminocyclopyrachlor), and the pyridine-2-carboxylates (picloram, clopyralid, and aminopyralid). In the last 10 years, two novel pyridine-2-carboxylate (or picolinate) herbicides were discovered at Dow AgroSciences. This paper will describe the structure activity relationship study that led to the discovery of the 6-aryl-picolinate herbicides Arylex™ active (2005) and Rinskor™ active (2010). While Arylex was developed primarily for use in cereal crops and Rinskor is still in development primarily for use in rice crops, both herbicides will also be utilized in additional crops.

Synthesis and Biological Potency of Anilino‐Triazine Insecticides

BACKGROUND An insecticide screening effort identified N-(4-bromophenyl)-4,6-bis(2,2,2-trifluoroethoxy)-1,3,5-triazine-2-amine as having weak potency against two lepidopteran species, Helicoverpa zea and Spodoptera exigua. A structure-activity relationship study about the trifluoroethoxy substituents and the aniline of this compound was carried out in an effort to improve insecticidal potency. RESULTS Initially, a series of analogs bearing various substituents on the aniline were prepared, and the insecticidal potency was evaluated against H. zea and S. exigua in greenhouse diet feeding assays. The results showed that electron-withdrawing substituents, such as Cl, Br and CF3 , were preferred over electron-donating substituents, such as methoxy, and that potency was significantly better when the substituent was in the para-position. Additional investigations showed that bis(anilino)trifluoroethoxytriazines were more potent. Replacement of the remaining trifluoroethyl group in the bis(anilino)triazine series with an alkyl amine lead to compounds of equal or superior efficacy. CONCLUSION The work presented showed that electron-withdrawing substituents in the para-position of the aniline ring of the initial hit delivered the best levels of insecticidal potency against the two insect species tested. Further investigations showed that potency could be improved by replacing one of the two trifluoroethoxy groups with additional 4-substituted aniline. This level of potency was maintained or further improved when the remaining trifluoroethoxy was replaced with a substituted amine.