Interaction of β-cyclodextrin as catalyst with acetophenone in asymmetric reaction: a theoretical survey

Abstract

The asymmetric reduction of acetophenone with sodium borohydride in the presence of β-cyclodextrin (β-CD) as catalyst can improve selectivity and yield. The interaction between acetophenone and β-CD plays an important role for the reduction of acetophenone. This work studies the reaction of acetophenone in the presence of β-CD using density functional theory (DFT) method. Energy is investigated to find out the lowest energy of two possible complexation models. The geometrical structure confirms that acetophenone inserts into the cavity mainly from the secondary hydroxyl side. Hydrogen bonds are researched on the basis of natural bonding orbital (NBO) analysis, the results confirm the donor-acceptor interactions of complex. Mülliken charge and frontier orbital are employed for revealing the electronic transfer. In addition, (13)C nuclear magnetic resonance ((13)CNMR) spectroscopy shows that the active site concentrates on the carbon atom of carbonyl group. The probable catalytic mechanism of β-CD is discussed in terms of the calculated parameters.

Cyclodextrins in Asymmetric and Stereospecific Synthesis

“…Moreover, it has been shown that the optical yields of the resulting alcohols also depend on the reaction temperature: ee significantly increased with a decrease of the reaction temperature. Wan et al [39] studied the interaction between acetophenone and β-CD in the complex and confirmed that acetophenone inserts into the cavity mainly from the secondary hydroxyls side. The results of the hydrogen bonds analysis confirmed the donor-acceptor interactions in the complex; while 13 C NMR results showed that the active site concentrates on the carbon atom of the carbonyl group.…”

Cyclodextrin-Catalyzed Organic Synthesis: Reactions, Mechanisms, and Applications

“…Similarly, the asymmetric reductions of prochiral ketones were also reported in different enantiometric excesses using modified cyclodextrins as supramolecular catalysts [ 53 , 54 ].…”