Asymmetric Michael addition of nitroalkanes to prochiral acceptors catalyzed by proline rubidium salts

Primary Amino Acid Lithium Salt-Catalyzed Asymmetric Michael Addition of Carbon Nucleophiles to Enones

“…The enantioselectivity was determined by HPLC analysis (77% ee, Daicel CHIRALPAK AD-H, 5% isopropanol/hexane, 1.0 mL/min, 229 nm; t r (major enantiomer) = 18. Spectroscopic data of γ-nitroketones 4 are in agreement with published data [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. …”

“…As pioneering works in organocatalytic asymmetric Michael addition of carbon nucleophiles to α,β-unsaturated carbonyl compounds, Yamaguchi's group reported that Michael addition of malonates to enones could be catalyzed by a proline alkali metal salt [6][7][8][9][10][11][12]. They later succeeded in the asymmetric Michael addition of nitroalkanes to enones using a proline rubidium salt-catalyst [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. We recently reported that an O-silylated L-serine lithium salt was an effective catalyst for asymmetric Michael addition of malonates to enones to give various 1,5-ketoesters in good yields with high enantioselectivity [33].…”

“…H NMR (400 MHz) and 13 C NMR (100 MHz) spectra were recorded on JEOL JNM-A400II FT NMR and ECX-400P. Chemical shifts,  are referred to TMS.…”

Michael Additions of Methylene Active Compounds to Chalcone in Ionic Liquids without any Catalyst: The Peculiar Properties of Ionic Liquids

“…It is of interest to note that the higher nucleophilicity of halide anions in IL than in conventional solvents was described by Chi et al, [38][39][40] and for water by Kim. [41] The higher nucleophilicity of halide anions in ionic liquids was made questionable in papers by Welton [42,43] and Landini. [44] Landini [44] proved that the nucleophilicities of halide ions and the azide ion in [hexmim]PF 6 are comparable with their nucleophility in methanol and is slightly lower than in DMSO. On the other hand, Welton [43] found that amines are more nucleophilic in 1-butyl-1-methylimidazolium trifluoromethylsulphonate and 1-butyl-1-methylpyrrolidinium trifluoromethylsulphonate than in dichloromethane and acetonitrile.…”

“…[1][2][3][4][5] The catalysts used include different bases, such as the rubidium salt of l-proline. [6][7][8] Organocatalysts have also been used for Michael additions of aldehydes and ketones to unsaturated carbonyl derivatives or nitrostyrenes. [9][10][11][12][13][14][15][16] Reactions are usually carried out either in DMSO or by using an excess of one reagent as the solvent.…”