Stereochemistry of 1,3-diheterocyclanes 4. Molecular and crystal structures of monosubstituted five-membered cyclic sulfites

Racemic and enantiopure cis-and trans-4-(1-naphthyloxy)methyl-2-oxo-1,3,2-dioxathiolanes were studied by X-ray diffraction. The factors responsible for their crystal packings were revealed. The conformation of the exocyclic fragment varies from synclinal to antiperiplanar depending on both the local (cis-trans isomerism of the molecule) and external (homochiral/heterochiral environment) stereochemical factors. Data on the structures of five-membered sulfites in crystals were generalized. It was concluded that the heterocycle has considerable conformational flexibility. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1095–1102, July, 2006.