Biphenylmethyl oxime ethers

Replacement of the normal pyrethroid ester by alternative linkages usually leads to diminution of biological activity. One important exception to this general phenomena is several oxime ether derivatives, in particular, 3-phenoxybenzyl derivatives of various alkyl aryl ketones. Pyrethroid esters derived from certain 2-substituted-[1,1 -biphenyl]-3-methanols have been shown to possess initial and residual activity surpassing that of esters derived from 3-phenoxybenzyl alcohol. Now it has been demonstrated that the same enhancement of activity was observed for alkyl aryl oxime ethers of certain [1,1 -biphenyl]-3-methanols compared to the corresponding 3-phenoxybenzyl alcohol derived oximes. The synthesis, biological activity, including soil activity, structure-activity relationships and toxicity of several of these biphenylmethyl oxime ethers are described. 

The activity of the 3-phenoxybenzyl alkyl aryl oxime ethers is reported to reside in the E-isomer. The activity of the E-isomer was compared with the activity of the E,Z alkyl aryl oxime ethers for this new series. This trend also occurs in the biphenylmethyl-methyl alkyl aryl oxime ethers (Table VI). 

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