Regioselective synthesis, characterization and antimicrobial evaluation of S-glycosides and S,N-diglycosides of 1,2-Dihydro-5-(1H-indol-2-yl)-1,2,4-triazole-3-thione

Abstract

Glycosylation of 1,2-Dihydro-5-(1H-indol-2-yl)-1,2,4-triazole-3-thione with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide, 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl bromide and 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-D-glucopyranosyl chloride was investigated in the presence of Et₃N and K₂CO₃ as acid scavengers. A regioselective S-glycosides were obtained by using Et₃N whereas, using K₂CO₃ gave a mixtures of two hybrids having two glycosidic bonds. The two products of each mixture were separated and characterized as S,N(1)- and S,N(2)-bis(glycosylated) derivatives. The structures of the newly synthesized compounds were elucidated by (1)H NMR, (13)C NMR, 2D NMR and mass spectra. The compounds were screened for their antibacterial and antifungal activities. Some compounds exhibited strong inhibition activity compared with the reference drugs (chloramphenicol and baneocin).

Keywords: 1,2,4-Triazoles; Antimicrobial; Bis(glycosides); Glycosylation; Indolyltriazoles.