Highly Flexible Synthetic Routes to Functionalized Phospholanes from Carbohydrates

Highly functionalized phospholanes 15, 17, and 26 and the corresponding diastereomers in which the configurations of the phospholane carbon-2 and carbon-5 are inverted can be readily prepared from d -mannitol by displacement of the appropriate dimesylate or cyclic sulfate with dilithiumphosphide reagents. The diols from which these ligands are prepared can also be converted into diarylphosphinite ligands. A route to related monophosphines bearing hemilabile tert- butylthio groups is also described. Complexes of these ligands and of related deprotected derivatives are potentially useful for enantioselective catalysis in organic and aqueous media.