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.