Reaction of Some Substituted 3-Aryl-4-formylsydnones with Tetra-Oacetyl- β-D-galactopyranosyl)thiosemicarbazide

Background: Thiosemicarbazones containing mono- or disaccharide moieties reveal several various remarkable biological activities; therefore these compounds have been focused in organic syntheses. Sydnone ring is the potential basic pharmacodynamic nucleus, which has been reported to possess a wide variety of biological activities such as antitumor, anticancer, anti-inflammatory, antiviral, and scavenging activities. The connection of monosaccharide moiety to sydnone ring could initiate the new activities. Methods: The synthetic reaction of different substituted 3-phenyl-4-formylsydnone N-(tetra-O-acetyl-β- D-galactopyranosyl)thiosemicarbazones was carried out under microwave-assisted heating conditions. The structures of obtained thiosemicarbazones were confirmed by IR, NMR and mass spectra. All obtained thiosemicarbazones were screened for DPPH radical scavenging ability. Results: Some different substituted 3-formyl-4-phenylsydnones were prepared by Vilsmeier-Haacks formylation reaction. These substituted 4-formylsydnones were converted into corresponding thiosemicarbazones by condensation with N-(2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyl)thiosemicarbazide. Some of these thiosemicarbazones showed remarkable DPPH radical scavenging ability. Conclusion: The efficient synthesis of 3-phenyl-4-formylsydnone N-(tetra-O-acetyl-β-D-galactopyranosyl) thiosemicarbazones under microwave-assisted refluxing conditions has been reported. Reaction yields were 40-80%. Obtained results showed that the compounds 4f and 4g have high antioxidant activity.