Synthesis and biological evaluation of novel β-hydroxy benzimidazolyl sulfone fluoroquinolones by selective oxidation using ammonium molybdate catalysed H2O2

Abstract

Synthesis of new β-hydroxy benzimidazolyl sulfides (4a-e) and β-hydroxy benzimidazolyl sulfones (5a-e) containing 7-piperazine fluoroquinolones have been described and evaluated for their antimicrobial activity. Benzoxazine fluoroquinolone carboxylic acid, 1, on reaction with piperazine in presence of triethylamine in acetonitrile under reflux resulted 7-piperazine bezoxazole fluoroquinolone, 2. The latter is reacted with epichlorohydrine in presence of NaOH in acetone yielded corresponding N-substituted epoxide, 3, with retained chirality, which on treatment with 5-substituted-2-mercaptobenzimidazoles given the corresponding β-hydroxy bezimidazolyl sulfides (4a-e). Further compounds 4a-e on treatment with H₂O₂ and ammonium molybdate in dichloromethane yielded the β-hydroxy bezimidazolyl sulfones, 5a-e. The antimicrobial activity of newly synthesized compounds along with levofloxacin (reference drug) were evaluated against different microorganisms and found many of the evaluated compounds have been exhibited remarkable activity.