Phenolic<i>N</i>-Oxide as a Highly Efficient Organocatalyst for Cyanosilylation of Ketones
作者:Xiaoming Feng、Yan Li、Bin He、Guolin Zhang
DOI:10.1055/s-2004-829072
日期:——
The use of an inexpensive, easy to handle and readily available chemical, 5 mol% phenolic N-oxide, alone as a catalyst for cyanosilylation of ketones gave the corresponding products in 78-99% yield with reaction times of 0.5-16 hours.
A new bifunctional catalytic system based on chiral N-oxide titanium complexes has been used for the asymmetric cyano-silylation of ketones. Screening of a variety of chiral N-oxide metal complexes resulted in (1R,2S)-1-(2'-pyridylmethyl)-2-(diphenylhydroxymethyl)pyrrolidine N-oxide titanium complex, which gave O-TMS cyanohydrins in good yields with enantiomeric excesses of up to 69%. A catalytic cycle