Abstract:
The crystal structure of the title compound, C30H38N2O5Si, has been investigated to establish the relative stereochemistry at the spiro ring junction and the two anomeric centres. Each of the O atoms in the tetrahydropyran rings adopts an axial position on the neighbouring ring. This bis-diaxial conformation is adopted, thus gaining maximum stablization from the anomeric effect. The silyl-protected hydroxymethyl and uracil substituents adopt equatorial positions on their associated tetrahydropyran rings, thereby minimizing unfavourable steric interactions. The dimeric (2'R*,6'R*,8'R*)- and (2'S*,6'S*,8'S*)-uridine units are connected to each other across crystallographic inversion centres via intermolecular N-HO hydrogen bonds.
