Synthesis and Antimicrobial Activity of Novel 2‐Substituted Phenoxy‐ N ‐(4‐substituted Phenyl‐5‐(1 H ‐1,2,4‐triazol‐1‐yl)thiazol‐2‐yl)acetamide Derivatives

A series of 2‐substituted phenoxy‐ N ‐(4‐substituted phenyl‐5‐(1 H ‐1,2,4‐triazol‐1‐yl)thiazole‐2‐yl)acetamide derivatives 8a , 8b , 8c , 8d , 8e , 8f , 8g , 8h , 8i , 8j , 8k , 8l , 8m , 8n , 8o , 8p , 8q , 8r , 8s , 8t was synthesized by the reaction of phenoxyacetyl chloride 7 with intermediate 4‐substituted phenyl‐5‐(1 H ‐1,2,4‐triazol‐1‐yl)thiazol‐2‐amine 5 . Their structures were confirmed by 1 H NMR, 13 C NMR, MS, IR, and elemental analyses. The synthesized compounds were also screened for their antimicrobial activity against three types of plant fungi ( Gibberella zeae , Phytophthora infestans , and Paralepetopsis sasakii ) and two kinds of bacteria [ Xanthomonas oryzae pv. oryzae ( Xoo ) and Xanthomonas axonopodis pv. citri ( Xac )] showing promising results. In particular, 8b , 8f , 8g , and 8h exhibited excellent antibacterial activity against Xoo , with 50% effective concentration (EC 50 ) values of 35.2, 80.1, 62.5, and 82.1 µg/mL, respectively, which are superior to the commercial antibacterial agent bismerthiazol (89.9 µg/mL). The preliminary structure–activity relationship studies of these compounds are also briefly described.