Asymmetric Henry reaction of aldehydes catalyzed by recyclable an MCM-41 supported copper(II) salen complex

A chiral modified MCM-41-Cu(salen) complex has been prepared and characterized by SEM, powder XRD, and EDX techniques as well as FT-IR and EPR spectroscopic methods. This new catalytic system was examined in the asymmetric Henry reaction between various aldehydes and nitromethane at room temperature. Aromatic, aliphatic, and heterocyclic aldehydes have been converted into the corresponding nitro alcohols in 60−92% yields with 60−90% ee. Several factors concerning the reactivity and enantioselectivity are also discussed. This catalyst was separated by filtration and reused several times without a significant loss of reactivity or enantioselectivity.

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1-Phenyl-2-nitroethanolC8H9NO3Ee = 90%[α]D24=-15.1 (c 1.18, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: (S)

1-(4-Methylphenyl)-2-nitroethanolC9H11NO3Ee = 80%[α]D24=-16.4 (c 1.78, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: (S)

1-(4-Methoxyphenyl)-2-nitroethanolC9H11NO4Ee = 82%[α]D24=-22.4 (c 1.78, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: (S)

1-(3-Methoxyphenyl)-2-nitroethanolC9H11NO4Ee = 85%[α]D24=-27.4 (c 1.78, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: (S)

1-(4-Nitrophenyl)-2-nitroethanolC8H8N2O5Ee = 87%[α]D24=-37.4 (c 1.78, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: (S)

1-(4-Chlorophenyl)-2-nitroethanolC8H8ClNO3Ee = 90%[α]D24=-17.4 (c 1.78, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: (S)

1-(4-Cyanophenyl)-2-nitroethanolC9H8N2O3Ee = 88%[α]D24=-33.2 (c 1.78, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: (S)

1-(1-Naphthyl)-2-nitroethanolC12H11NO3Ee = 88%[α]D24=-26.2 (c 1.78, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: (S)

1-Nitro-4-phenyl-but-3-en-2-olC10H11NO3Ee = 90%[α]D24=-22.2 (c 1.78, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: (S)

1-Nitro-2-heptanolC11H15NO3Ee = 60%[α]D24=-16.9 (c 2.1, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (S)