Synthesis of Rhodium Complexes with Chiral Diene Ligands via Diastereoselective Coordination and Their Application in the Asymmetric Insertion of Diazo Compounds into E-H Bonds.

Abstract

A new method for the synthesis of chiral diene rhodium catalysts is introduced. The readily available racemic tetrafluoro-benzobarrelene complexes [(R 2 -TFB)RhCl] 2 \xa0were separated into two enantiomers via selective coordination of one of them with the auxiliary\xa0 S -salicyl-oxazoline ligand. One of the resulting chiral complexes with an exceptionally bulky diene ligand [( R,R -iPr 2 -TFB)RhCl] 2 \xa0proved to be an efficient catalyst for the asymmetric insertion of diazoesters into B-H and Si-H bonds giving the functionalized organoboranes and silanes with high yields (79-97%) and enantiomeric purity (87-98% ee). The stereoselectivity of separation via auxiliary ligand and that of the catalytic reaction was predicted by DFT calculations.