The Reaction of Epoxy Benzocycloalkenes with Diborane

Abstract

The epoxides formed from the following olefins have been treated with diborane and the products characterized: 1H-indene, 1,2-dihydronaphthalene, 6,7-dihydro-5H-benzocycloheptene, 5,6,7,8-tetra- hydrobenzocyclooctene, 6,7,8,9-tetrahydro-5H-benzocyclononene, 1- and 2-methyl-1H-indene, and 4-and 3-methyl-1,2-dihydronaphthalene. The major product from the unsubstituted epoxides is the β-hydroxy compound, but the proportion of the cehydroxy compound increases with increasing ring size. The methyl-substituted oxirans generally evolve hydrogen on treatment with diborane, and oxidation leads to diol products.