Substrate binding in the asymmetric dihydroxylation reaction - Investigation of the stereoselectivity in the dihydroxylation of C-s-symmetric divinylcarbinol derivatives

The mechanism of the asymmetric dihydroxylation (AD) reaction has been hotl y disputed. We have studied the stereochemical outcome of the AD reaction o n a series of C-s-symmetric divinylcarbinol derivatives in order to shed Li ght on the binding mode of the substrate to the osmium tetroxide-ligand com plex. The product distribution is dependent on the size of the allylic subs tituent, and on the type and class of ligand. It is postulated that the dia stereospecificity of the reactions originates from attractive forces betwee n the substrate and the ligand. These interactions are independent of the i nteractions responsible for the enantioselectivity in the AD reaction.