Study On The Asymmetric Reduction Of Substituted Acenaphthenequinones Using Plant Cells

Chiral polycyclic aromatic alcohols with rigid structures are widely used as synthetic building blocks for pharmaceuticals intermediates, transition metal ligands, analytical reagents and functional materials. Although the enantioselective reduction of prochiral ketones is the most important and powerful method for the preparation of enantiomerically pure alcohols, the reduction of ketones with this structure is still extremely challenging due to high steric hindrance caused by rigid structures of polycyclic aromatic ketones. In this paper, regio- and enantioselective reduction of substituted acenaphthenequinones were conducted under mild conditions using plant cells. The (+)- and (-)-mono-hydroxyacenaphthenones were achieved with high conversion and good enantiomeric purity.The plant-catalyzed reduction of acenaphthenequinones proceeded in neutral aqueous solution, and vigorous agitator was applied in order to facilitate the reaction. The conversion and enantioselecitivity were determined by HPLC. The experimental results indicate that plants can only reduce one carbanyl group of acenaphthenequinones and afford pure mono-hydroxyl ketone. A screening of 15 plants allowed the selection of two suitable plants fulfilling enantiocomplementarity. The (+)-mono-hydroxyacenaphthenone (conversion 98%, 71% ee) was achieved using Peach (Prunus persica (L.) Batsch.), and (-)-mono-hydroxyacenaphthenones (conversion 95%, 81% ee) using Carrot (Daucus carota L.).The substituted acenaphthenequinones were synthesized with acenaphthenenquinone as raw material by reaction of bromination, nitration, substitution, thermal decomposition and diazotization. In order to explore the scope of the reactions catalyzed by carrot root and peach fruit, the 6-substituted acenaphthenequinones were examined under the same reaction conditions. Similar to the plant-catalyzed reduction of acenaphthenequinone, the reduction of 6-substituted acenaphthenequinones catalyzed by carrot and peach gave corresponding mono-hydroxyacenaphthenones with high regionselectivities. However, the different substituted groups have significant influence on the conversation and enantioselectivity.The study provides another example of proving that enantiocomplementarity can be achieved by enzyme-catalyzed method, and open up the use of plant cells as potent reducing agent for the reduction of polycyclic aromatic ketons.In the chapter 4, a 1,8-naphthalimide fluorescent probe(N1) is designed and synthesized for Co²⁺. Upon the interaction with Co²⁺, sensor N1 showes signal changes in both fluorescent spectra and absorption spectra. H1 probaly is the first two-channel molecular switcher for the optical detection of Co²⁺. Further studies for the properties of N1 are still in proceeding.