Importance of chiral phase-transfer catalysts with dual functions in obtaining high enantioselectivity in the Michael reaction of malonates and chalcone derivatives.
[reaction: see text]. Highly enantioselective Michael addition of diethyl malonate to chalcone derivatives has been achieved under mild phase-transfer conditions by the successful utilization of N-spiro C(2)-symmetric chiral quaternary ammonium bromide 1 as a catalyst, which possesses diarylhydroxymethyl functionalities as a recognition site for the prochiral electrophile. This simple asymmetric Michael addition process was found to be quite effective for various chalcone derivatives, including those with heteroaromatic substituents.
Ooi
Takashi
T
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Japan.
Ohara
Daisuke
D
Fukumoto
Kazuhiro
K
Maruoka
Keiji
K