Difluorphos, an electron-poor diphosphane: A good match between electronic and steric features

The π acidity makes the difference: The fluorinated diphosphane, difluorphos, is synthesized (see structure: purple = P, red = O, green = F, gray = C) and its stereoelectronic features are evaluated in theoretical and experimental studies. Its unusual π acidity explains the excellent results obtained with it in ruthenium-mediated asymmetric hydrogenation of fluorinated β-functionalized ketones. These results are better than those obtained with other biphenyl-based diphosphanes.