An improved protocol for the RuO4-catalyzed dihydroxylation of olefins.

[reaction: see text] Dihydroxylation under ruthenium catalysis provides an easy access to syn-diols, although overoxidation is a common side reaction. Furthermore, the high catalyst loadings offset the lower price of ruthenium compared to osmium. In this paper, we present an improved protocol for the RuO(4)-catalyzed syn-dihydroxylation using only 0.5 mol % catalyst under acidic conditions. A variety of olefins can be hydroxylated in good to excellent yields with only minor formation of side products.