Molecular and crystal structure of isosteviol sulphite

The molecular and crystal structure of isosteviol sulphite (1) is studied by means of the X-ray crystallographic analysis. It is demonstrated that this compound has a "dimer" structure, i.e. two isosteviol molecules are bound with a sulphite bridge. The molecule takes a tweezers-like conformation stabilized by intramolecular hydrogen bonds of acid groups. The molecules in the crystal are bound by intermolecular C-H center dot center dot center dot O hydrogen bonds.