Although commercially used for decades, sales of protoporphyrinogen-IX oxidase (protox, PPO) inhibitors have grown recently due in part to glyphosate weed resistance. Substituted N-aryluracils were first discovered in the late eighties at Hoffman-La Roche as an extremely active subclass of PPO inhibiting herbicides. Uniroyal soon developed interest in flupropacil but it was not until 2001 that butafenacil was commercialized by Syngenta and saflufenacil introduced by BASF in 2009. In the mid-nineties, George Theodoridis at FMC reported that propionate-substituted N-phenoxyphenyltriazolinones were very active protox-inhibiting herbicides. Sumitomo subsequently found that oxyacetate-substituted N-aryloxyphenyluracils were also very potent herbicides, with broad-spectrum activity against broadleaf and grass weeds. Here, we wish to report on the synthesis and herbicidal activity of structurally related acetal ester-substituted N-phenoxyphenyluracils such as 1 where we had special interest in the burndown activity on glyphosate resistant weeds.

Exploring phenoxyphenyluracil acetal esters as PPO-inhibiting burndown herbicides

248th National Meeting (2014)

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