Theoretical Study On The Catalytic Effect Of Cyclodextrin And Its Derivative In Organic Reaction

In this paper, the density functional theory(DFT) method is employed to study the effect of cyclodextin(CD) and modified cyclodextin in organic reaction. The following four systems are included.(1) Interaction of β-cyclodextrin as catalyst with acetophenone in asymmetric reaction;(2) The per-6-amino-β-cyclodextrin as catalyst in synthesis of2-aryl-2,3-dihydro-4-quinolones;(3) Theβ-cyclodextrin catalyzes benzyl azide and phenyl acetylene in synthesis of 1,2,3-triazoles;(4) The interaction of β-cyclodextrin catalyst with p-chlorobenzonitrile for synthesis of 5-substituted 1H-tetrazoles in n,n-dimethylformamide.The asymmetric reduction of acetophenone with sodium borohydride in presence of?-CD as catalyst can improve selectivity and high yield. The interaction between acetophenone and ?-CD plays an important role for the reduction of acetophenone. We study the reaction of acetophenone in the presence of ?-CD using DFT method. Energy is investigated to find out the lowest energy of two possible complexation models. The geometrical structure confirms that acetophenone insert into the cavity mainly from the secondary hydroxyl side. Hydrogen bonds are researched on the basis of natural bonding orbital(NBO) analysis. Mülliken charge and frontier orbital are employed for revealing the electronic transfer. However,13 C nuclear magnetic resonance(13C NMR)spectroscopy shows that the active site concentrates on the carbon atom of carbonyl group. The probable catalytic mechanism of ?-CD is discussed in terms of the calculated parameters.The synthesis of 2-aryl-2,3-dihydro-4-quinolones in presence of per-6-amino-β-cyclodextrin(per-6-ABCD) as catalyst can improve selectivity and yield.The interaction between per-6-ABCD and benzaldehyde or o-aminoacetophenone plays an important role in this reaction. We study the complexes of per-6-ABCD with benzaldehyde and o-aminoacetophenone using DFT method. The reaction process is investigated by studying the energy of the reactants and the product. Hydrogen bonds are researched on the basis of NBO analysis. The Mülliken charge and frontier orbital are employed for revealing the charge distribution. In addition, 13 C NMR spectroscopy shows that the carbon atom on the aldehyde group for benzaldehyde, carbonyl group and the carbon atom connected with carbonyl group for o-aminoacetophenone are activated apparently in the cavity of per-6-ABCD.The phenyl acetylene and benzyl azide cycloaddition reaction in water in presence of ?-CD as a phase transfer catalyst(PTC) can get a better yield in a shorter time. Theinteraction between ?-CD and phenyl acetylene or benzyl azide plays an important role in this reaction. We study the complexes of ?-CD with phenyl acetylene and benzyl azide using DFT method. In order to find out the orientations of guests in the cavity of ?-CD,binding energy and deformation energy are investigated and the calculated results are confirmed by 1H NMR. The data from single point energy indicate that the inclusion complexes can improve the solubilities of phenyl acetylene and benzyl azide in water.The 13 C and 15 N NMR show that the most obvious variation concentrates on C6 and C8 of phenyl acetylene and N15 of benzyl azide in complexes. Mülliken charge and frontier orbital are employed for revealing the charge distribution.The synthesis of 5-substituted 1H-tetrazoles in n,n-dimethylformamide(DMF) with?-CD as catalyst can get an excellent yield in short reaction times. We study the complex of ?-CD with p-chlorobenzonitrile using DFT method. The minimum energy structure is investigated in water, DMF and DMSO. Hydrogen bonds are researched on the basis of NBO analysis. The relative position between p-chlorobenzonitrile and ?-CD in DMF is confirmed by1 H NMR. The data from13 C and15N spectra indicate that more positive charges focus on the carbon atom of cyanogroup(C11) and more negative charges concentrate on the the nitrogen atom of cyanogroup(N12) upon complexation. The results from frontier molecular orbitals and Mülliken charge reveal that β-CD catalyst improves the reactivity and electrophilicity of p-chlorobenzonitrile, meanwhile, the functional group of p-chlorobenzonitrile is easier to be attacked by azide ions in presence of β-CD as catalyst.