1. Lewis Acid Chemistry at the Edge of Ferrocene
Frieder Jäkle, Department of Chemistry Rutgers University, Newark, NJ 07102
Planar chiral ferrocenes play important roles as ligands in transition metal-catalyzed processes. However, their counterparts, the planar chiral ferrocene-based Lewis acids, have not been studied despite the importance and widespread use of chiral Lewis acids in organic synthesis.
We have now succeeded in the preparation of the first enantiomerically pure planar chiral ferrocenylborane Lewis acids:
Facile resolution of the planar chiral ferrocenyl-borane was accomplished by highly stereo-selective chelation with N-methylpseudo-ephedrines.
Studies on the allylation of ketones with chiral (ferrocenyl)allylboranes proceeded smoothly and with stereoselectivities of upto 80% ee.