Structure and conformation of Hoffer's chlorosugar and the related β-azido and β-nitrile sugar.

Hoffer's chlorosugar is an important, universal building block for the synthesis of nucleosides with artificial nucleobases, but its solid-state structure has remained undetermined. Herein we report on the single-crystal X-ray structure of Hoffer's chlorosugar, as well as the structural characterization of the related β-azido and β-nitrile sugars. Their crystal structures show similar intermolecular interactions and related supramolecular structures. Together, these structural elucidations and pseudorotational analyses close the longstanding gap in the characterization of important carbohydrate building blocks for the synthesis of artificial nucleosides.