Stereochemistry of Ionic Thiol Addition to Acetylenic Ketones

Abstract
Piperidine-catalysed addition of thiols to benzoyl- and p-chlorobenzoyl-phenylacetylenes in benzene gave a mixture of (E)- and (Z)-1-aryl-3-arylthio-3-phenyl-2-propen-1-ones. However, in methanol or aqueous 1,4-dioxane only the (Z)-isomers were obtained. Configurational assignments to the isomers were based on NMR, UV, and IR spectroscopy.