Asymmetric addition of trimethylsilyl cyanide to aldehydes promoted by chiral polymeric vanadium(V) salen complex as an efficient and recyclable catalyst
作者:Noor-ul H. Khan、Santosh Agrawal、Rukhsana I. Kureshy、Sayed H.R. Abdi、Vishal J. Mayani、Raksh V. Jasra
DOI:10.1016/j.tetasy.2006.09.024
日期:2006.10
The asymmetric addition of trimethylsilyl cyanide to various aldehydes catalyzed by efficient new vanadyl polymeric salen complexes having 12 repeating salen units was investigated at room temperature. An excellent yield of the trimethylsilylether of cyanohydrins (up to 98%) with high chiral induction (96%) in case of 2-methylbenzaldehyde was achieved in 18 h. The catalyst recovered four times with
A highly enantioselective addition of trimethylsilylcyanide to aldehydes catalyzed by chiral titanium complexes is described. The chiral titanium complexes were prepared in situ from Ti((OPr)-Pr-i)(4) and beta-hydroxyamide ligands, that could easily be synthesized from ketopinic acid and C-2 symmetrical chiral diamines in a small number of steps. (C) 2004 Elsevier Ltd. All rights reserved.