Synthesis and antitubercular activity of nucleoside analogs based on L-ascorbic acid and bases

5,6-O-isopropylidene-2,3-di-O-methyl ascorbic acid (2), obtained by reaction of acetone with ascorbic acid (1) followed by methylation with methyl iodide, on 1,8-Diazabicyclo[5.4.0]undec-7-ene-catalyzed elimination of acetone moiety led to the formation of respective 2,3-di-O-methyl didehydro-L-ascorbic acid (4) in good yield. The latter, on methanesulfonylation with methanesulfonyl chloride and subsequent reaction of the crude methanesulfonyloxy derivative with imidazole, benzimidazole, and adenine resulted in the corresponding tetronolactonyl nucleoside analogs 5, 6, and 7. Compound 5 on reaction with benzyl amine led to the N-benzylated teramyl nucleoside analog, while compounds 6 and 7 did not react under similar conditions. All the synthesized compounds were evaluated for their antitubercular activity against M. tuberculosis H37Ra and H37Rv, exhibiting a minimum inhibitory concentration (MIC) of more than12.5 μg/mL.