AROMATIC SUBSTITUENT EFFECT ON THE STEREOSELECTIVITY OF THE ACID-INDUCED RING-OPENING OF 1,2-EPOXIDES DERIVED FROM 3,4-DIHYDRONAPHTHALENE -IMPORTANCE OF THE REACTIVE CONFORMATIONS FOR THE STEREOSELECTIVITY

The stereochemistry of the acid-induced ring opening reactions (hydrol ysis, methanolysis and trichloroacetolysis) of 1,2-epoxides derived fr om ring-substituted 3,4-dihydronaphthalene has been examined. In every case, a satisfactory Hammett-type linear correlation was found betwee n the diastereoselectivity of the reaction and the sigma+ constant of the aromatic substituent. The stereoselectivity of the opening reactio n turned out to be largely driven by the reactive conformation of the epoxide and/or of the opening process intermediates.