Methanesulfonamide: a Cosolvent and a General Acid Catalyst in Sharpless Asymmetric Dihydroxylations
Mikko H. Junttila and Osmo O. E. Hormi*
*Department of Chemistry, University of Oulu, P.O. Box 3000, FIN-90014 Oulu, Finland, Email: osmo.hormioulu.fi
M. H. Junttila, O. O. E. Hormi, J. Org. Chem., 2009, 74, 3038-3047.
In Sharpless dihydroxylations of long chain olefins, methanesulfonamide is a cosolvent that aids in the transfer of the hydroxide ions from the water phase to the organic phase. In asymmetric dihydroxylations of conjugated aromatic olefins, the weakly acidic methanesulfonamide is a general acid catalyst that protonates the intermediate osmate esters.
see article for more examples
proposed phase transfer catalysis
Sodium Chlorite as an Efficient Oxidant and Hydroxy Ion Pump in Osmium-Catalyzed Asymmetric Dihydroxylation
M. H. Junttila, O. E. O. Hormi, J. Org. Chem., 2004, 69, 4816-4820.