Sy. Jonsson et al., Osmium-catalyzed asymmetric dihydroxylation of olefins by H2O2 using a biomimetic flavin-based coupled catalytic system, J AM CHEM S, 123(7), 2001, pp. 1365-1371
Selective cis-dihydroxylation of olefins with the aid of a triple catalytic
system using H2O2 as the terminal oxidant has been developed. In this proc
ess Os(VI) is recycled to Os(VIII) by a coupled electron-transfer-mediator
system based on N-methylmorpholine and a biomimetic flavin, leading to a mi
ld and selective electron transfer. Aliphatic, aromatic, and functionalized
olefins were successfully cis-dihydroxylated, employing the triple catalyt
ic system. The present biomimetic catalytic system works well in asymmetric
dihydroxylation and gave optically active diols in good isolated yields an
d high enantiomeric excesses (up to 99% ee).