Pure Appl. Chem., 2006, Vol. 78, No. 2, pp. 519-523
doi:10.1351/pac200678020519
Asymmetric protonation of silyl enolates catalyzed by chiral phosphine-silver(I) complexes*
Akira Yanagisawa, Taichiro Touge, and Takayoshi Arai
Department of Chemistry, Faculty of Science, Chiba University, Yayoi-cho 1-33, Inage, Chiba 263-8522, Japan
Abstract:
A catalytic asymmetric protonation of trimethylsilyl enolates was achieved using a 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP)-silver(I) fluoride complex as a chiral catalyst in a mixed solvent consisting of dichloromethane and methanol. Various nonracemic ketones possessing a tertiary asymmetric carbon at the α-position were prepared with high enantioselectivity up to 99 % ee.
Keywords: alcohol; asymmetric catalysis; protonation; silver; silyl enolate.
*Pure Appl. Chem. 78, 197-523. An issue of reviews and research papers based on lectures presented at the 13th IUPAC International Symposium on Organometallic Chemistry Directed Towards Organic Synthesis (OMCOS-13), Geneva, Switzerland, 17-21 July 2005.