Selective Approaches to Synthesize New Series of Heterocyclic Compounds Derived from Metronidazole

Abstract

A series of novel azo compounds was synthesized from Metronidazole through the reduction of its nitro group to an amine, yielding 2-(5-amino-2-methyl-1H-imidazol-1-yl) ethanol. The study comprised three main stages to produce new compounds with potential biological activity. In the first stage, the nitro group of Metronidazole was reduced to an amine. This intermediate then underwent two synthetic pathways. In the first pathway, Schiff bases were prepared by reacting the amine with various aldehydes, followed by conversion into heterocyclic derivatives. In the second pathway, the amine was transformed into a diazonium salt and subsequently coupled with phenolic compounds to obtain azo dyes. Specifically, the azo derivatives were synthesized by reacting compound with sodium nitrite at 0–5 °C, followed by coupling with several pharmaceutical compounds-paracetamol, 4-aminoantipyrine, Metronidazole reductase, sulfanilic acid, and salicylic acid-to yield compounds. Additionally, Schiff bases were synthesized by reacting compound with m-anisaldehyde, vanillin, and 3-nitrobenzaldehyde to produce compounds. These Schiff bases were then cyclized using thioglycolic acids and phthalic anhydrides to afford new heterocyclic compounds: thiazolidines and oxazepanes. The synthesized compounds were characterized by physical constants and spectral analyses, including infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy.