Preparation of Triazole Mannose Derivatives from Galactaric Acid and Study their Antibacterial Activity

Abstract

In order to investigate new triazoles further, mannose derivatives were created. D-mannaric acid was first produced by oxidizing mannose with diluted nitric acid. 2,3,4,5-tetra-O-acetyl- mannaric acid was produced by acetylating d-mannaric acid with acetic anhydride, yielding the completely protected derivative having acetyl groups at positions (2,3,4,5). The acid chloride derivative produced by treating 2,3,4,5-tetra-O-acetyl- mannaric acid with thionyl chloride was then transformed into the semicarbazide and phenyl semicarbazide derivatives. The production of the bis-triazolyl derivatives was successfully achieved by intramolecular cyclization in the presence of potassium hydroxide. Additionally, we investigated the antibacterial activity of the produced compounds against two other strains of bacteria: Streptococcus pneumonia and Staphylococcus aureus. Some of these strains had the best antibacterial activity, matching that of the common antibiotic amoxicillin. Infrared spectra (IR) and nuclear magnetic resonance (NMR) for proton 1HNMR spectroscopy were used to confirm all derivatives.