101. Enantioselective Nickel-Catalyzed Hydrocyanation using Chiral Phosphine-Phosphite Ligands: Recent Improvements and Insights
- Author
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Gary S. Nichol, Alberto Cavalieri, Hans-Günther Schmalz, Dieter Vogt, and Anna Falk
- Subjects
Chemistry ,Enantioselective synthesis ,chemistry.chemical_element ,General Chemistry ,Medicinal chemistry ,Catalysis ,chemistry.chemical_compound ,Nickel ,Hydrocyanation ,Organic chemistry ,Selectivity ,Tetrahydrofuran ,Cyclooctadiene ,Phosphine - Abstract
The asymmetric hydrocyanation of vinylarenes was investigated using hydrogen cyanide (HCN) in the presence of 5 mol% of a catalyst prepared from a phenol-derived chiral phosphine-phosphite ligand and bis(cyclooctadiene)nickel [Ni(cod)2]. The reactions were performed in tetrahydrofuran (THF) at room temperature to give exclusively the branched nitriles with superior enantioselectivities of 88–99% ee for vinylarenes and 74–94% ee for vinylheteroarenes, respectively. Using styrene as a model substrate it was shown that the catalyst loading could be decreased to 0.42 mol% without any loss of selectivity (88% ee). The structure of the pre-catalyst, i.e., a tetrahedral Ni(0)(P,P-chelate)(cod) complex, was proven by X-ray and NMR analysis. Additional insight into the reaction course was gained by monitoring the hydrocyanation of styrene-d8 by means of 2D NMR spectroscopy.
- Published
- 2015