Efficient synthesis of novel 2-deoxy-C-nucleosides containing oxa and thiadiazole derivatives and their biological activity

Abstract

Five membered oxa- and thiadiazole derivatives have shown significant biological activity due to their unique bioisosteric properties. Herein, we describe an efficient synthetic approach leading to several novel C-nucleosides containing an oxadiazole or thiadiazole ring system. This work provides for the first-time ability to assemble β-C-nucleosides in a facile manner offering an ideal framework for the possible development of new antiviral and antitumor drugs. All new C-nucleosides were tested for their activity against TBEV and SARS-CoV-2. Two of the synthesized compounds exerted mild anti-SARS-CoV-2 activity, as evidenced by the decrease in viral titers by <1 log10 PFU/ml compared with controls. Mechanism for the formation of 5-substituted 1,3,4-thiadiazole ring is proposed and a structure-activity relationship established with these C-nucleosides.