The preparation and dihydroxylation of a series of polyenes and cyclic allylic alcohols using the TMEDA/osmium tetroxide mixture is reported. Remarkably, these reagents lead to high levels of regiochemical and stereochemical control as the oxidant hydrogen-bonds to the allylic alcohol group. A mechanistic hypothesis is presented which invokes the formation of a reactive, bidentate complex between osmium tetroxide and TMEDA at low temperatures.
