Synthesis of Nitro compounds by 1,4-addition of active methylenes
The ionic liquid [bmIm]OH is a catalyst and a reaction medium for Michael additions. Although the addition to α,β-unsaturated ketones gives the monoaddition products, this ionic liquid always drives the reaction of open-chain 1,3-dicarbonyl compounds with α,β-unsaturated esters and nitriles toward bis-addition.
B. C. Ranu, S. Banerjee, Org. Lett., 2005, 7, 3049-3052.
A (-)-cinchonine modified squaramide, easily prepared through a two-step process from methyl squarate, was shown to be an effective catalyst, even at catalyst loadings as low as 0.1 mol%, for the conjugate addition reactions of 1,3-dicarbonyl compounds to β-nitrostyrenes. The addition products were obtained in high yields and excellent enantioselectivities.
J. P. Malerich, K. Hagihara, V. H. Rawal, J. Am. Chem. Soc., 2008, 130, 14416-14417.
An axially chiral guanidine catalyst facilitated the highly enantioselective 1,4-addition reaction of 1,3-dicarbonyl compounds with a broad range of conjugated nitroalkenes and showed extremely high catalytic activity.
M. Terada, H. Ube, Y. Yaguchi, J. Am. Chem. Soc., 2006, 128, 1454-1455.
A new bifunctional catalyst bearing a thiourea moiety and an amino group was highly efficient for the asymmetric Michael reaction of 1,3-dicarbonyl compounds to nitroolefins to afford the Michael adducts with high enantio- and diastereoselectivity.
T. Okino, Y. Hoashi, T. Fukukawa, X. Xu, Y. Takemoto, J. Am. Chem. Soc., 2005, 7, 119-125.
A Ni(II)-(bis)diamine-catalyzed, highly enantioselective Michael addition of substituted and unsubstituted malonates and β-ketoesters to nitroalkenes bearing aromatic and aliphatic residues has been developed.
D. A. Evans, D. Seidel, J. Am. Chem. Soc., 2005, 127, 9958-9959.