Stereochemistry of the Addition of Bromine to Acenaphthylene Derivatives: Substituent and Solvent Effects

Abstract

Addition of bromine to acenaphthylene and 5-bromoacenaphthylene in aprotic solvents of different polarity is not stereospecific: both trans and cis isomers of the corresponding 1,2-dibromides are formed. In general, the relative proportion of syn addition increases with decreasing solvent polarity; the highest percentage of cis products is observed in 1,4-dioxane. The stereochemistry of bromine addition to nine additional 3-, 5-, and 5,6-substituted acenaphthylenes in dioxane is reported. A number of new cis-1,2-dibromoacenaphthenes have been isolated for the first time.