Preferred boat conformations in unsaturated sulphur heterocycles; X-ray analysis of cis-1,4-dimethylisothiochroman 2,2-dioxide
Abstract
In the 1,4- and 1,3-dimethylisothiochroman 2,2-dioxides, the cis- and trans-forms respectively, are shown to be the more thermodynamically stable stereoisomers; a preferred boat conformation is inferred for these compounds and is demonstrated by a crystallographic study of the cis-1,4 isomer (17).