Enantio- and diastereoselective Michael reaction of 1,3-dicarbonyl compounds to nitroolefins catalyzed by a bifunctional thiourea.
We synthesized a new class of bifunctional catalysts bearing a thiourea moiety and an amino group on a chiral scaffold. Among them, thiourea 1e bearing 3,5-bis(trifluoromethyl)benzene and dimethylamino groups was revealed to be highly efficient for the asymmetric Michael reaction of 1,3-dicarbonyl compounds to nitroolefins. Furthermore, we have developed a new synthetic route for (R)-(-)-baclofen and a chiral quaternary carbon center with high enantioselectivity by Michael reaction. In these reactions, we assumed that a thiourea moiety and an amino group of the catalyst activates a nitroolefin and a 1,3-dicarbonyl compound, respectively, to afford the Michael adduct with high enantio- and diastereoselectivity.
Okino
Tomotaka
T
Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.
Hoashi
Yasutaka
Y
Furukawa
Tomihiro
T
Xu
Xuenong
X
Takemoto
Yoshiji
Y