N-Thiophenylethyl-2,2-dichloro-1-cyclopropanecarboxamides: modification of the amide part of carpropamid and examination of fungicidal activity

The synthetic route for a halo-substituted thiophenylethyl variant of blasticide carpropamid is described. First, halo-substituted acetylthiophene was homologated to thiophenylacetic acid using Pb(OAc)4 and BF3OEt2, followed by reduction to CH2CH2OH with NaBH4/I2 or BH3Me2S, and then to the azide via the tosylate. The azide was transformed to the amine using triphenylphosphine, which was then allowed to react with the corresponding acyl chloride to yield the final amide product. Fungicidal tests of 50 related products for gray mold and downy mildew on cucumber, and leaf rust and powdery mildew on wheat were conducted in 500 mg/l on pot. Many compounds showed efficacy to control these plant diseases. It should be noted that several blasticide-oriented compounds displayed high control effectiveness on downy mildew.