Asymmetric Michael Addition of Malonate Anions to Prochiral Acceptors Catalyzed by l-Proline Rubidium Salt
摘要:
L-Proline rubidium salt catalyzes the asymmetric Michael addition of malonate anions to prochiral enones and enals. This method can be applied to a wide range of substrates to give adducts with a predictable absolute configuration: (S)-adducts from (E)-enones/enals and (R)-adducts from cyclic (Z)-enones. Both the secondary amine moiety and the carboxylate moiety are critical for the catalytic activity and asymmetric induction. Varying the countercation also affects the reaction course. High enantiomeric excesses were attained when di(tert-butyl) malonate was added to (E)-enones in the presence of CsF. The stereochemistry of the Michael reaction indicates that asymmetric induction takes place via enantioface discrimination involving the acceptor alpha-carbon atom rather than the beta-carbon atom.
Asymmetric Michael Addition of Malonates to Enones Catalyzed by a Primary β-Amino Acid and Its Lithium Salt
作者:Masanori Yoshida、Mao Narita、Shoji Hara
DOI:10.1021/jo201429w
日期:2011.10.21
Highly enantioselective Michaeladdition 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
A new C2-symmetric heterobimetallic complex as a promoter for asymmetric Michael addition reactions
作者:G. Manickam、G. Sundararajan
DOI:10.1016/s0957-4166(97)00234-6
日期:1997.7
C2-symmetric chiral amino diol (1R,5R)-3-aza-3-benzyl-1,5-diphenyl pentan-1,5-diol [(R,R)-I] has been synthesised by a modified procedure. The heterobimetalliccatalyst [I2AlLi] obtained by reaction of the amino diol [(R,R)-I] with LiAlH4, promotes asymmetricMichaeladdition of malonic esters and thiophenols to α,β-unsaturated compounds with high enantiomeric excess.