Base-induced eliminations of the vinylogous β-hydroxysilanes 7, 9, 11 and 12 are stereospecifically, giving largely the,-diene 8 from 7 and 11, the,-diene 10 from 9, and the,- diene 13 from 12. When a double bond is produced, it is selectively placed adjacent to the carbon atom that originally carried the hydro
