Effect of conformational control of chiral oxazaborolidine by π–π stacking interaction of a pentafluorophenyl group toward asymmetric borane reduction

A pentafluorophenyl group can act as a stereo-controlling group in oxazaborolidine-catalyzed asymmetric borane reduction through intramolecular π–π stacking interaction with a phenyl group. The intramolecular π–π interaction in oxazaborolidine bearing pentafluorophenyl group is confirmed by calculations and 1H NMR study. The interaction affects the enantioselectivity of the asymmetric reduction of acetophenone while the extent is small.

Graphical abstractA pentafluorophenyl group can act as a stereo-controlling group in oxazaborolidine-catalyzed asymmetric borane reduction through intramolecular π–π stacking interaction with a phenyl group. Figure optionsDownload full-size imageDownload as PowerPoint slide