A highly enantioselective tandem Michael/ring‐closurereaction of α,β‐unsaturated pyrazoleamides and amidomalonates has been accomplished in the presence of a chiral N,N′‐dioxide–Yb(OTf)3 complex (Tf: trifluoromethanesulfonyl) to give various substituted chiral glutarimides with high yields and diastereo‐ and enantioselectivities. Moreover, this methodology could be used for gram‐scale manipulation
Enantioselective Michael Additions of Nitromethane by a Catalytic Double Activation Method Using Chiral Lewis Acid and Achiral Amine Catalysts
作者:Kennosuke Itoh、Shuji Kanemasa
DOI:10.1021/ja027313+
日期:2002.11.1
with 1-(2-alkenoyl)-3,5-dimethylpyrazoles can be effectively catalyzed by R,R-DBFOX/Ph.Ni(ClO4)2.3H2O and achiral amine bases, each in a catalytic loading of 10 mol %, to give 1-(3-substituted 4-nitrobutanoyl)-3,5-dimethylpyrazoles in high chemical yields. Excellent enantioselectivities up to 98% ee have been achieved. The nitro moiety can be easily reduced on Raney nickel at atmospheric pressure, followed