Synthesis and antimicrobial evaluation of arylated 1,3,5-triphenyl pyrazoline derivatives using suzuki-miyaura reactions

Abstract

The first palladium –catalyzed coupling reactions of 1,3,5-triphenyl pyrazoline are reported. The Suzuki-Miyaura reaction of 3-(4-bromophenyl)-1,5-diphenyl pyrazoline with one equivalent of arylboronic acids afforded 3-(biphenyl)-1,5-diphenyl pyrazoline in 53-78 % yield. While the Suzuki-Miyaura reactions of 3,5-bis(4-bromophenyl)-1-phenyl pyrazoline with two equivalent of arylboronic acids gave 3,5-bis(biphenyl)-1-phenyl pyrazoline in 55-80% yield. The characterization of the synthesized derivatives (5a-h) and (6a-h) were accomplished on the basis of NMR, FT-IR, and mass techniques. The newly pyrazoline derivatives have been investigated for their in vitro antibacterial activity against gram- negative and gram-positive bacteria. The di-coupling compounds (6a-h) exhibited promising antibacterial against all four bacterial strains compared to the mono-coupling compounds (5a-h) which displayed a slight activity. The compound 6d showed a potent activity significantly more active than Trimethoprim (100μg/ml).