Semisynthesis of some benzamide, benzenesulfonamide, and thioureido-4,5-dimethylthiophene derivatives as a new class of antimicrobial agents

The natural alkaloid 2-amino-l-phenylpropan-1-ol (1) was utilized in the synthesis of some novel benzamides (2-5), benzenesulfonamides (6-8) and ethyl 2-(3-(1-hydroxy-1-phenylpropan-2-yl)thioureido)-4,5-dimethylthiophene-3-carboxylate (9). The structures of the semisynthesized compounds were proved by analytical and spectral data. The synthesized compounds were evaluated in vitro for antimicrobial activity against Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 35501, Candida albicans ATCC 14053 and Aspergillus niger ATCC 16404. Two compounds showed inhibitory effect against C. albicans ATCC 14053: ethyl 2-(3-(1-hydroxy-1-phenylpropan-2-yl)thioureido)-4,5-dimethylthiophene-3-carboxylate (9) was the most active with MIC = 1.5 mg/mL followed by 4-bromo-N-(1-hydroxy-1-phenylpropan-2-yl)benzenesulfonamide (8) with MIC = 3 mg/mL.