Synthesis and Antimicrobial Screening of Novel Thioglycosides and Acyclonucleoside Analogs Carrying 1,2,3-Triazole and 1,3,4-Oxadiazole Moieties

ABSTRACT The solvent-free 1,3-dipolar cycloaddition reaction of dimethylacetylene dicarboxylate (1) with 2-chlorophenyl azide (2) afforded 1,2,3-triazole diester 3 that upon hydrazinolysis, furnished the corresponding bis-acid hydrazide 4. The treatment of compound 4 with carbon disulfide in a refluxing potassium hydroxide solution furnished the desired bis-1,3,4-oxadiazole-2-thione 5 tethered to a 1,2,3-triazole moiety. The respective SOx-glycosides 9–11 were obtained by glycosylation of bis-oxadiazole 5 with 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide (6), 2,3,4,6-tetra-O-acetyl-α-d-galactopyranosyl bromide (7), and 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-d-glucopyranosyl chloride (8) in dry acetone in the presence of Et3N, which acted as a base. However, alkylation of 5 with halogeno-alkanol 12 or 13, chloroglycerol 14, bromoethers 20 or 21, and epichlohydrin 22 in the presence of K2CO3 in DMF yielded the corresponding acyclonucleoside analogs 16–18 and 23–25. The isopropylidenes 19 and acetyl derivatives 26–28 of the products were also prepared. The newly synthesized compounds were characterized by 1H NMR, 13C NMR, 2D NMR, and mass spectra. The compounds were screened for their antibacterial and antifungal activities. A number of the tested compounds exhibited significant antimicrobial activity compared to the reference drugs.