Synthesis of Novel 1‐(5‐(Benzylsulfinyl)‐3‐methyl‐1,3,4‐thiadiazol‐2(3 H HH )‐ylidene)‐thiourea/urea Derivatives and Evaluation of Their Antimicrobial Activities

摘要

> A new series of 1‐(5‐(benzylsulfinyl)‐3‐methyl‐1,3,4‐thiadiazol‐2(3 H )‐ylidene)‐thiourea/urea derivatives ( 1a – j ) were designed and synthesized. For the first time, (i) a new process was developed for N ‐methylation of 1,3,4‐thiadiazole moiety using dimethyl carbonate an environmentally benign reagent in presence of N , N , N′ ,N ′ ‐tetramethylethylenediamine and (ii) the sulfide was selectively oxidized to sulfoxide in higher yield by using chlorine (g) in aqueous acetic acid media under mild reaction condition. The synthesized compounds ( 1a – j ) were investigated for their antimicrobial activities. The tested compounds ( 1a – j ) were exhibited moderate to excellent antibacterial activities against both Gram‐positive and Gram‐negative bacterial strains. The same compounds exhibited good antifungal activities against selected fungal strains. Particularly, the compounds 1b , 1d , 1h , and 1i were proved to be promising leads exhibiting both antibacterial and antifungal activities compared with standard drugs, ciprofloxacin, and fluconazole. The presence of 1,3,4‐thiadiazole moiety has a significant role in the display of antimicrobial activity. In addition, the presence of both sulfinyl and thiourea or urea functionalities has enhanced the activity as per obtained antimicrobial activity data.