Design, Synthesis and Antibacterial Evaluation of Some New Pyrrolidine Derivatives Based Pyrazole Moiety via Vilsmeier-Haack Reaction

The following work involved synthesizing a new series of substituted Pyrrolidine/4H-Pyrazole-4-carbaldehyde derivatives [IV]a-e derived from captopril known as an angiotensin converting enzyme inhibitor drug, using the Vilsmeier-Haack reaction. There were some steps involved for synthesizing new hydrazone compounds [III]a-e via refluxing equal mole of captopril hydrazide [II] with different substituted aromatic ketone (acetophenone, 4-hydroxyacetophenone, 4-aminoacetophenone, 4-nitroacetophenone, and 4-bromoacetophenone) in benzene via condensation reaction. The newly substituted 4H-pyrazole-4-carbaldehyde derivatives [IV]a-e are obtained via a cyclization reaction of substitute hydrazones [III]a-e heating with POCl3/DMF, under Vilsmeier–Haack reaction. The prepared pyrrolidine derivatives-based pyrazole moiety compounds were designed, synthesized, and confirmed by spectral methods (FT-IR, 1H-NMR, and Mass Spectra). Screening of synthesized compounds against two types of pathogenic display very good efficacy opposite these classes of bacteria utilizing Ampicillin as a traditional antibiotic.