Iminium salt catalysts for asymmetric epoxidation: the first high enantioselectivities. 
A highly enantioselective iminium salt catalyst has been prepared and tested in the catalytic asymmetric epoxidation of unfunctionalized alkenes, giving up to 95% ee, the highest ee yet reported for iminium salt-catalyzed epoxidation.  Catalyst loadings as low as 0.1 mol % may be used.