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

• Published in: Angewandte Chemie International Edition 2021-08, Vol.60 (34), p.18712-18720
• Main Authors: Ankudinov, Nikita M., Chusov, Denis A., Nelyubina, Yulia V., Perekalin, Dmitry S.
• Format: Article
• Language: English
• Subjects: Asymmetry; carbene insertion; Catalysts; Chemical bonds; Chemical synthesis; Coordination compounds; DFT calculations; diene ligands; Enantiomers; Insertion; Ligands; Rhodium; rhodium complexes; Stereoselectivity
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202105179

A new method for the synthesis of chiral diene rhodium catalysts is introduced. The readily available racemic tetrafluorobenzobarrelene complexes [(R2‐TFB)RhCl]2 were separated into two enantiomers via selective coordination of one of them with the auxiliary S‐salicyl‐oxazoline ligand. One of the resulting chiral complexes with an exceptionally bulky diene ligand [(R,R‐iPr2‐TFB)RhCl]2 was 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. Rhodium complexes with bulky racemic dienes were synthesized and separated into pure enantiomers by diastereoselective coordination with a chiral auxiliary ligand. The optimal structure of the auxiliary ligand and the selectivity of coordination were predicted by density functional theory calculations. The resulting chiral complexes catalyze the asymmetric insertion of diazoesters into B−H and Si−H bonds.