Chelation, dihydroxylations, osmium tetroxide

The chelating nature of the diamine precludes osmate ester hy-droysis in situ and means that the oxidation of an alkene requires 1 equiv of osmium tetroxide, followed by a step to release the glycol. However, the use of catalytic amounts of transition metal in the directed dihydroxylation of allylic amides was shown to be possible (eq 31) by using a monodentate amine (quinuclidine, which is released in situ from quinuclidine-A(-oxide). These conditions are catalytic in osmium but generally exhibit a less powerful directing effect than stoichiometric osmium tetroxide and TMEDA. 

---