Branched-chain C-cyano pyranonucleosides: Synthesis of 3′-C-cyano & 3′-C-cyano-3′-deoxy pyrimidine pyranonucleosides as novel cytotoxic agents

► A stereoselective synthesis of 3'-C-branched chain nucleosides was accomplished. ► 3'-C-branched chain nucleosides was prepared and chemically characterized. ► The novel compounds were evaluated for their antitumor and antiviral activity. ► The 5-fluorouracil derivative, proved to be highly cytostatic.