Binaphthol-Based Diphosphite Ligands in Asymmetric Nickel-Catalyzed Hydrocyanation of Styrene and 1,3-Cyclohexadiene: Influence of Steric Properties
✍ Scribed by Jos Wilting; Michèle Janssen; Christian Müller; Martin Lutz; Anthony L. Spek; Dieter Vogt
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 130 KB
- Volume
- 349
- Category
- Article
- ISSN
- 1615-4150
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✦ Synopsis
Abstract
A series of chiral (R)‐binaphthol‐based diphosphite ligands with different substituents was prepared and applied in the asymmetric nickel‐catalyzed hydrocyanation of styrene and 1,3‐cyclohexadiene to investigate the influence of their steric properties. The optimum steric properties for the hydrocyanation reaction lie within a narrow window. With the optimized ligand, hydrocyanation of styrene gave full conversion (Subs/Ni=100) with 49 % ee, the TON was determined to be 600. Hydrocyanation of 1,3‐cyclohexadiene gave 50 % conversion (Subs/Ni=500) with an excellent ee of 86 %. This demonstrates that high __ee__s are not only accessible for vinylarenes but also for conjugated dienes in the asymmetric nickel‐catalyzed hydrocyanation.