Combined bead polymerization and Cinchona organocatalyst immobilization by thiol–ene addition

• Kim A. Fredriksen,
• Tor E. Kristensen and
• Tore Hansen

Beilstein J. Org. Chem. 2012, 8, 1126–1133, doi:10.3762/bjoc.8.125

• also tested in the Michael addition of methyl malonate to trans-β-nitrostyrene (Table 4) [21]. The catalyst gave quantitative yield and excellent enantioselectivity after 3–4 days reaction time. However, the catalyst exhibited poor recycling properties as yields fell sharply after the second reaction

• determined by HPLC analysis (Chiralpak AD-H, 2% iPrOH in isohexane, 1.0 mL/min): tR = 19.2 min and 26.2 min. General procedure for asymmetric Michael addition of methyl malonate to trans-β-nitrostyrene: trans-β-Nitrostyrene (83.4 mg, 0.56 mmol) and methyl malonate (0.23 g, 1.78 mmol) were dissolved in

Enantioselective Michael addition of 2-hydroxy-1,4-naphthoquinones to nitroalkenes catalyzed by binaphthyl-derived organocatalysts

• Saet Byeol Woo and
• Dae Young Kim

Beilstein J. Org. Chem. 2012, 8, 699–704, doi:10.3762/bjoc.8.78

• elements [45][46][47]. We initially investigated the reaction system with 2-hydroxy-1,4-naphthoquinone (1) and nitrostyrene 2a in the presence of 10 mol % of Takemoto's catalyst I in acetonitrile at room temperature, to determine the optimum reaction conditions for the catalytic, enantioselective Michael

• III are matched, thus enhancing the stereochemical control, whereas in the diastereomeric catalyst VII this is not the case. Different solvents were then tested in the presence of 10 mol % of catalyst III together with 2-hydroxy-1,4-naphthoquinone (1) and nitrostyrene 2a in order to further improve

Catalyst-free and solvent-free Michael addition of 1,3-dicarbonyl compounds to nitroalkenes by a grinding method

• Zong-Bo Xie,
• Na Wang,
• Ming-Yu Wu,
• Ting He,
• Zhang-Gao Le and
• Xiao-Qi Yu

Beilstein J. Org. Chem. 2012, 8, 534–538, doi:10.3762/bjoc.8.61

• [22], a transition-metal-free process for the synthesis of substituted dihydrofurans [23] and a catalyst-free tandem reaction for the synthesis of 5-hydroxy-1,5-dihydro-2H-pyrrol-2-ones in aqueous medium [24]. Recently, when carrying out the reaction of β-nitrostyrene with 1,3-cyclopentanedione under

• . Results and Discussion In our initial study, equimolar amounts of β-nitrostyrene (1a) and 1,3-cyclopentanedione (2a), as a model reaction (Table 1, entry 1), were mixed and ground in a mortar at room temperature. The mixture became sticky and adhered to the wall of the mortar firmly after a few seconds

• solvents gave much lower yields. In fact, there are few reports on the Michael addition of β-nitrostyrene and 1,3-cyclopentanedione. Hrnčiar and Čulák performed the same reaction in methanol using sodium methylate as a catalyst; however, only 85% of product 3a was obtained, and a longer reaction time was