Methylene group modifications of the N-(isothiazol-5-yl)phenylacetamides. Synthesis and insecticidal activity

It has been shown that oxidation at the ct-carbon of N-(4-chloro-3-methyl-5 -isothiazolyl)-2-[p-[(alpha,alpha,alpha-trifluoro-p-tolyl)oxy]phenyl] aceta mide (1) is conveniently brought about using dimethylformamide dimethylacet al to give N-(4-chloro-3-methyl-5-isothiazolyl)-beta-(dimethylamino)-p-[(al pha,alpha,alpha-trifluoro-p-tolyl)oxy]atropamide (2), which has served as a common starting point for a variety of functional group transformations. T hese transformations were found to proceed in moderate to good yields to gi ve derivatives of 1 that retained much of the efficacy associated with the parent amide and have allowed for an expansion of the SAR to be developed. Examples of enamines, enols, enol (thio)ethers, oximes, and hydrazones were prepared. In particular, the enamines derived from law molecular weight am ines and amino acids were most active as broad-spectrum insecticides and we re found to be even more active than 1 on root-knot nematode.