Stereoselective synthesis of 4′-selenonucleosides using the Pummerer glycosylation reaction

The syntheses of four selenonucleosides, namely 4′-β-selenoadenosine, -cytidine, -thymidine, and -uridine are described. Commercially available d-ribonolactone was converted to the key intermediate 1,4-anhydro-4-seleno-d-ribitol in seven steps in overall excellent yield. Oxidation of the seleno-d-ribitol with MCPBA gave a single diastereomeric selenoxide in excellent yield, which upon Pummerer reaction in the presence of silylated purine or pyrimidine bases gave stereoselectively the corresponding 4′-β-selenonucleosides. The stereochemistry at the anomeric center was determined by means of 1D-NOE experiments.

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