Fine Modification of Salen Ligands – Effects on the Salen–Ti-Catalyzed Asymmetric Cyanosilylation of Aldehydes

✍ Scribed by Chengwei Lv; Qigan Cheng; Daqian Xu; Shoufeng Wang; Chungu Xia; Wei Sun

• Publisher: John Wiley and Sons
• Year: 2011
• Tongue: English
• Weight: 211 KB
• Volume: 2011
• Category: Article
• ISSN: 1434-193X
• DOI: 10.1002/ejoc.201100319

✦ Synopsis

Abstract

New bifunctional N‐oxide salen–Ti^IV^ complexes and a pyrrolidine salen–Ti^IV^ complex in combination with achiral N‐oxide were developed and applied to the asymmetric addition of trimethylsilyl cyanide to aldehydes. Notably, both enantiomers of trimethylsilyl ethers of cyanohydrins could be easily prepared by modifying the catalysts employed in this reaction, which are based on the same chiral diamine collar derived from L‐tartaric acid. The products were obtained generally with moderate to good enantiomeric excesses and excellent yields by using relatively low catalyst loadings and only 1.05 equivalents of trimethylsilylcyanide (TMSCN).