Osmium-catalyzed dihydroxylation of alkenes by H2O2 in room temperature ionic liquid co-catalyzed by VO(acac)2 or MeReO3

Room temperature ionic liquid [bmim]PF6 was used to immobilize a bimetallic catalytic system for H2O2-based dihydroxylation of alkenes. Osmium tetroxide was used as the substrate-selective catalyst with either VO(acac)2 or MeReO3 as co-catalyst. The latter serve as an electron transfer mediator (ETM) and activates H2O2. For an increased efficiency N-methylmorpholine is required as an additional ETM in most cases. A range of alkenes were dihydroxylated using this robust bimetallic system and it was demonstrated that for some of the alkenes the catalytic system can be recycled and used up to five times.

A practical and useful catalytic system for dihydroxylation of alkenes by H2O2 was obtained by immobilization of OsO4 and a co-catalyst (VO(acac)2 or MeReO3 (MTO)) in an ionic liquid. The presence of N-methylmorpholine (NMM) as an additional co-catalyst (electron transfer mediator) increased the efficiency of the dihydroxylation in most cases. In a preliminary experiment an enantioselective dihydroxylation with this system was obtained.Figure optionsDownload as PowerPoint slide