Synthesis and Biological Activity of Ethyl 4‐Alkyl‐2‐(2‐(substituted phenoxy)acetamido)thiazole‐5‐carboxylate

Abstract

A series of novel ethyl 4‐(methyl or trifluoromethyl)‐2‐(2‐(substituted phenoxy)acetamido)thiazole‐5‐carboxylates 7a, 7b, 7c, 7d, 7e and 8f, 8g, 8h, 8i, 8j, 8k, 8l, 8m, 8n, 8o, 8p, 8q, 8r were synthesized, and their structures were confirmed by IR, 1H‐NMR, MS spectra and elemental analysis. The results of preliminary bioassays show that some of the title compounds exhibit moderate to good herbicidal activities. Compared with the fluorine free compounds 7a, 7b, and 7e, the compounds bearing fluorine 8g, 8j, and 8q showed higher herbicidal activities with 70–100% inhibition against Capsella bursa‐pastoris, Amaranthus restroflexus, and Eclipta prostrata at the dosage of 150 g/ha, which indicated that the trifluoromethyl on the thiazole ring was beneficial for the herbicidal activity. Furthermore, compounds 8f, 8g, 8h, 8i, 8j, 8k, 8l, 8m, 8n, 8o, 8p, 8q, 8r were tested for fungicidal activity against Pseudoperonospora cubensis at 500 µg/mL. Compounds 8f and 8q showed the best fungicidal activity with more than 80% inhibition.