First synthesis of 4′-selenonucleosides showing unusual southern conformation

Abstract

(Chemical Equation Presented) The first synthesis of 4′- selenonucleosides was achieved using a Pummerer-type condensation as a key step. All stereoelectronic effects shown in 4′-oxonucleosides were overwhelmed by the size of selenium and steric interactions, driving the conformation to the C2′-endo/C3′-exo twist (Southern) conformation. © 2008 American Chemical Society.