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

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, 1 H‐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.