The use of fluorinated alcohols as solvents, cosolvents or additives in homogeneous catalysis is reviewed. The effect of these particular compounds on efficiency, regioselectivity and stereoselectivity of metal-catalyzed reactions, as well as on reactions mediated by organocatalysts, is described. Where available in several cases, the effect of fluorous alcohols on the catalytic mechanism is analyzed in detail and rationalized by their unique physical and chemical properties. In most instances, a comparison to the effect of commonly employed solvents is elaborated.

Primed! Secondary phosphine oxides are able to tautomerize in situ to phosphinous acids and then coordinate to soft transition metals through the trivalent phosphorus atom (see scheme). The presence of a chiral backbone allows this reaction to run stereoselectively and be used for the generation of highly enantioselective homogeneous catalysts.

Three sets of new and related chiral phospholane and phosphepine ligands have been prepared for Rh-catalyzed enantioselective hydrogenation. The size and substitution pattern of the cyclic monophosphanes were varied. More importantly, the ligands differ in the nature of the heterocyclic group linked to the trivalent phosphorus atom: 2-pyridone or 2-alkoxypyridine. In the corresponding Rh complexes, the pyridone units of two monodentate P ligands can assemble by hydrogen bonding and form chelates. In contrast, synthetic precursors bearing alkoxypyridine appendages are not able to aggregate via intramolecular hydrogen bonds. The nature of self-assembly is dependent on the nature of the P ligand and the solvent used for the hydrogenation (CH2Cl2 vs. MeOH). These features affect the rate of the reaction as well as the enantioselectivity, which varied in the range of 0-99 % ee Complexation studies and DFT calculations were performed to explain these differences.

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Scharf gemacht! Sekundäre Phosphinoxide können in situ zu phosphinigen Säuren tautomerisieren und anschließend über das dreiwertige Phosphoratom an weiche Übergangsmetalle koordinieren (siehe Schema). Dank eines chiralen Rückgrats kann diese Reaktion stereoselektiv ablaufen und zur Generierung hoch enantioselektiver homogener Katalysatoren eingesetzt werden.