HPLC enantioseparation of racemates using novel pillared homochiral metal–organic framework–silica composite as chiral stationary phase has been successfully demonstrated.

The last frontier in the development of chiral stationary phases for chromatographic enantioseparation involves homochiral metal–organic frameworks (MOFs). Using enantiopure (R)-2,2′-dihydroxy-1,1′-binaphthalene-6,6′-dicarboxylic acid as a starting material, we prepared three homochiral MOFs that were further used as chiral stationary phases for high-performance liquid chromatography to separate the enantiomers of various kinds of racemic sulfoxides, sec-alcohols, β-lactams, benzoins, flavanones and epoxides. The experimental results showed excellent performances for enantioseparation, and highlighted that enantioseparation on homochiral MOF columns is practical.

A strong asymmetric amplification was observed in the enantioselective Henry reaction catalyzed by the (R,R)-trans-N,N′-bis-biphenyl-4-ylmethyl-cyclohexane-1,2-diamine·CuCl2 complex in AcOEt, while no amplification occurred in MeOH.

Novel 46-membered chiral rhombamine macrocycles (R,R,R,R)-8a and 8b were synthesized by [2+2] cyclocondensation reactions of (R,R)-1,2-diaminocyclohexane with the corresponding dialdehydes and subsequent reduction with NaBH4. The X-ray crystal structure of 1:4 dioxane complex with (R,R,R,R)-8a indicated a rhombus conformation of the chiral macrocycle. Compounds (R,R,R,R)-8a and 8b were tested as chiral shift reagents for a wide range of α-substituted carboxylic acids and amino acid derivatives. Enantiodiscrimination of 1H NMR signals was observed with ΔΔδ values of up to 0.214 ppm.C66H68N4[α]D25 = −18 (c 0.1, CHCl3)Source of chirality: (1R,2R)-diaminocyclohexaneAbsolute configuration: (R,R,R,R)C64H64N4O2[α]D25 = −40 (c 0.1, CHCl3)Source of chirality: (1R,2R)-diaminocyclohexaneAbsolute configuration: (R,R,R,R)

Solvent-free asymmetric aldol reactions between cyclohexanone and 4-nitrobenzaldehyde using chiral amine macrocycle–metal(II) complexes as catalysts in a ball mill afforded the anti-aldol product as the major isomer with up to 93% ee.

Enantiomeric resolution of various sulfoxides using a homochiral MOF–silica composite as a new chiral stationary phase for HPLC has been successfully demonstrated.

A novel three component gel is obtained from the reaction of succinic acid, Cu(NO3)2, and 1,4-diaza-bicyclo[2.2.2]octane (DABCO) in various organic solvents. The presence of the three components is essential for gelation in the solvents.

Enantiomeric resolution of various sulfoxides using a homochiral MOF–silica composite as a new chiral stationary phase for HPLC has been successfully demonstrated.

A strong asymmetric amplification was observed in the enantioselective Henry reaction catalyzed by the (R,R)-trans-N,N′-bis-biphenyl-4-ylmethyl-cyclohexane-1,2-diamine·CuCl2 complex in AcOEt, while no amplification occurred in MeOH.