and 3a–m using trimethylsilyl cyanide and triphenylphosphine supported on polystyrene as a catalyst undersolvent-freeconditions. It has been shown that a small amount of the catalyst allows the chemoselective 1,2-addition of trimethylsilyl cyanide to α,β-unsaturated carbonyls 1a–g (5 mol%) and to saturated carbonyls 3a–m (2 mol%). The preparation of cyanohydrintrimethylsilylethers 2a–g and 4a–m
Thiourea-Catalyzed Enantioselective Cyanosilylation of Ketones
作者:Douglas E. Fuerst、Eric N. Jacobsen
DOI:10.1021/ja052511x
日期:2005.6.1
The new chiral amino thiourea catalyst 3d promotes the highly enantioselective cyanosilylation of a wide variety of ketones. The hindered tertiary amine substituent plays a crucial role with regard to both stereoinduction and reactivity, suggesting a cooperative mechanism involving electrophile activation by thiourea and nucleophile activation by the amine.
Synthesis of β-Cyano Ketones Promoted by a Heterogeneous Fluoride Catalyst