No abstract

Highly enantioselective Michael addition of malonates to enones was achieved using a mixed catalyst consisting of a primary β-amino acid, O-TBDPS (S)-β-homoserine, and its lithium salt. Various cyclic and acyclic enones were converted into 1,5-ketoesters in high yields (up to 92%) with high enantioselectivity (up to 97% ee) under mild reaction conditions. Details of synthesis of the catalyst, optimization of the reaction conditions for the Michael addition reaction, and a plausible reaction mechanism are described.

Abstract-Siloxy amino acid lithium salt, O-tert-butyldiphenylsilyl L-serine lithium salt, was found to be an effective catalyst for the asymmetric Michael addition reaction of malonates to enones.

Asymmetric Michael addition of carbon nucleophiles, nitroalkanes and a β-ketoester, to enones was investigated by using a primary amino acid lithium salt as a catalyst.

Asymmetric Michael Addition of Malonates to Enones Catalyzed by a Primary β-Amino Acid and Its Lithium Salt. -The title reaction allows an efficient access to a number of optically active 1,5-ketoesters. -(YOSHIDA*, M.; NARITA, M.; HARA, S.; J. Org. Chem. 76 (2011) 20, 8513-8517, http://dx.doi.org/10.1021/jo201429w ; Dep. Chem. Process Eng., Fac. Eng., Hokkaido Univ., Sapporo 060, Japan; Eng.) -Jannicke 08-085