Akio Manabe

Synthesis and Fungicidal Activity of 1-(α-tert-Butylcinnamoyl)imidazoles

Several 1-(α-tert-butylcinnamoyl)imidazoles were prepared to examine their fungicidal activity. The (Z)-4-chlorocinnamoyl derivative was prepared from (anti)-2-tert-butyl-3-(4-chlorophenyl)-3-hydroxypropanoic acid by treating with 1,1′-carbonyldiimidazole and a subsequent β-elimination reaction at an elevated temperature. The (Z)-isomer of the 4-chlorocinnamoyl derivative showed good fungicidal activity against Erysiphe graminis and Botrytis cinerea in pot tests, whereas the corresponding (E)-isomer derived from the (Z)-isomer through photoisomerization was much less active.

Steric structure–activity relationships of the rice blasticide, S-2900 (diclocymet)†

The four diastereomers of 2-cyano-N-[1-(2,4-dichlorophenyl)ethyl]-3,3-dimethyl-butyramide were prepared by a direct HPLC separation with chiral columns. The [(S)acid, (R)amine]-isomer was the most antifungal among the diastereomers tested. Because of the lability of the clinical group in the acid moiety, the (RS)-(R)-isomer is being developed as a rice blasticide. (S-2900, proposed common name diclocymet).