A general procedure for the osmium-catalyzed dihydroxylation
of various olefins using bleach as oxidant is reported for the first
time. Aromatic and aliphatic olefins yield the corresponding cis-1,2-diols in the presence of dihydroquinine
or dihydroquinidine derivatives (Sharpless ligands) with good to
excellent chemo- and enantioselectivities under optimized pH conditions.
In the presence of a small excess of bleach as reoxidant fast dihydroxylation
takes place even at 0 °C. Under optimum reaction
conditions it is possible to dihydroxylate terminal aliphatic and
aromatic olefins as well as internal olefins. The low price of the
oxidant and the simple handling of bleach make this dihydroxylation
variant attractive for further applications.
asymmetric catalysis - dihydroxylation - homogenous catalysis - osmium - oxidations