Synthesis Of Chiral 1–phenyl–1,2–ethanediol Derivatives Catalyzed By Plant Cells

Chiral 1–phenyl–1,2–ethanediol derivatives, containing two hydroxyl groups and the aromatic ring, can be carried out transformation of a series of functional groups. They can be used as precursors of some drugs by appropriate modification or transformation of construction, some chiral 1–phenyl–1,2–ethanediol derivatives have certain biological activity by themselves. Therefore, chiral 1–phenyl–1,2–ethanediol derivatives as the ideal chiral building blocks, are potentially important synthetic intermediates for the preparation of pharmaceuticals, agrochemicals, and pheromones, For example, the optically pure 1–phenyl–1,2–ethanediol is an important chiral dopants in Liquid Crystals and other microelectronic materials which can shorten the response time of LCD screen and prevent breakout phenomenon. It is an important way to prepared chiral alcohol by asymmetric reduction of prochiral ketones. Among numerous methods of ketone asymmetric reduction, biocatalysis using higher plants have been paid more attention in recent years.Firstly,α–hydroxyketones were synthesized and reaction condition was optimized to make the yield up to 77.0%. Then, theα–hydroxyketones were reductioned by NaBH4, the racemic 1–phenyl–1,2–ethanediol derivatives were analysed by HPLC equipped with chiral columns, which can be used as the reference for bioreduction.In this paper, enantioselective reduction ofα–hydroxyacetophenone,α–hydroxy– 4'–methylacetophenone,α–hydroxy–4'–methoxyacetophenone,α–hydroxy–4'–chloro acetophenone andα–hydroxy–3'–chloroacetophenone, was studied using carrot cells to Prelog's configurated vicinal diols. The effects of various crucial factors, including the shape of commuted plant, reaction temperature, reaction medium, substrate concentration and reaction time, on the conversion ofα–hydroxyl aromatic ketones and optical activity of aryl vicinal diols were researched by One–factor experimental design, The optimal reaction condition was obtained after the investigation. The results inferred that the conversion of substrates and the enantiomeric excess of product were clearly affected by both electronic effect and steric effect of substituted group. Using carrot as biocatalyst, distiller water as reaction medium, under the optimal condition, chiral aryl vicinal diols were obtained with good yield and excellent enantioselectivity, the conversion ofα–hydroxyl– acetophenone can reach to 92.1%, while the conversion ofα–hydroxy–4'–methylacetophenone,α–hydroxy–4'– methoxyacetophenone,α–hydroxy–4'–chloroacetophenone,α–hydroxy–3'–chloro– acetophenone were 52.1%,51.4%,65.3% and 67.2% respectively, and all of the enantioselectivity of corresponding R–1,2–aryl vicinal diols also could be as high as 98.9%. Furthermore, in order to optimize the condition of the asymmetric reduction and determine the principal and subordinate order of factors effecting on the conversion ofα–hydroxyacetophenone and enantimeric excess of (R)–1–phenylethane–1,2–diol,α–hydroxyacetophenone was reduced as a typic model substrate using carrot cells.