Seven-Membered Ring Nucleoside Analogues: Stereoselective Synthesis and Studies on Their Conformational Properties

The
synthesis of a novel series of seven-membered ring nucleoside
analogues as candidates for biological screening and gene silencing
applications is described. The key step in the synthetic approach
is a stereoselective synthesis of an epoxide that is used as a common
synthetic intermediate to prepare functionalized oxepane nucleoside
derivatives. The conformational landscape and preferred ring-puckering
of selected oxepane nucleosides was also studied by NMR, X-ray crystallography,
and quantum mechanical calculations.