Substituent effects in the selective reductive opening of epoxides with borohydrides in the presence of beta-cyclodextrin

The opening of ortho-substituted phenyl oxiranes by borohydrides is described both in aqueous and solid phases. Some remarkable differences in the regioselectivity and inversion of enantioselectivity of oxirane ring-opening are reported. The results obtained are compared with previous studies and have allowed some factors governing the reactivity, the regio- and stereoselectivity of this reaction to be evaluated. Preferential orientations of the substrate included inside the cyclodextrin are proposed from these results. Copyright 1999 Wiley-Liss, Inc.