Ytterbium perfluorooctanesulfonate

The synthesis, reactions, and biological properties of substituted imidazoles have a significant role in modem heterocyclic chemistry. Multi-substituted imidazoles, an important group of pharmaceutical compounds, show a wide spectrum of biological activity [38]. Synthesis of trisubstituted imidazoles was successfully carried out using rare earth(III) perfluorooctanesulfonates [RE(OPf)3, RE = Sc, Y, La-Lu] as catalysts in fluorous solvents. Ytterbium perfluorooctanesulfonate [Yb(OPf)3] catalyzes the... 

As an alternative to the use of fluorous tag, fluorous aqueous biphasic systems have also been explored. Recently, fluorous biphasic system composed of fluorous Lewis acid ytterbium perfluorooctanesulfonate [Yb(OPf)3], fluorous solvent perfluorocarbon has been used in the synthesis of benzodiazepines from OPD and carbonyl compounds [127]. Conceptually, the fluorous catalyst with perfluoroalkylated tails can dissolve into the fluorous phase containing the product after the reaction. The study has been extended later to the use of fluorous aqueous emulsion expecting that the organic substrate will remain in the interfacial area between a fluorous phase and aqueous media. Thus another synthesis of benzodiazepines has been reported by the same group by carrying out the reaction in a fluorous aqueous emulsion system composed of perfluorooctane and potassium perfluorooctanesulfonate at room temperature (Scheme 38) [128]. Moreover, the emulsion could be recovered and recycled without significant loss of activity. 

W.-B. Yi, C. Cai, Ytterbium perfluorooctanesulfonate-benzodiazepine derivatives in fluorous solvents, Synth. Commun. 37 (2007) 3827-3833. 

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