Synthesis, characterization and antimicrobial activity of new chalcones and their 6-aryl-4-(2,5-dichlorothiophen-3-yl)-6H-1,3-thiazin-2-amine derivatives

Chalcones (5a-h) were prepared in high yields via the condensation of 3-acetyl-2,5-dichlorothiophene (3) with aryl aldehydes (4a-h). The reaction of the resulting chalcones with thiourea in the presence of a catalytic amount of hydrochloric acid provided the 1,3-thiazin-2-amine derivatives (6a-g) in moderate yields. All new compounds were characterized by extensive NMR analysis data, including 1D NMR experiments (1H and 13C) and 2D NMR experiments (COSY, HMBC, HSQC), as well as ESIMS and HRESIMS data. The newly synthesized compounds were evaluated for their biological activities, which demonstrate a very good to low bioactivities as antibacterial and antifungal, respectively.