School of Chemistry and Chemical Engineering, Queen's University Belfast, David Keir Building, Belfast, BT9 5AG, UK.
Dalton Trans. 2012 Nov 21;41(43):13423-8. doi: 10.1039/c2dt31781h.
Chemoenzymatic dynamic kinetic resolution (DKR) of rac-1-phenyl ethanol into R-1-phenylethanol acetate was investigated with emphasis on the minimization of side reactions. The organometallic hydrogen transfer (racemization) catalyst was varied, and this was observed to alter the rate and extent of oxidation of the alcohol to form ketone side products. The performance of highly active catalyst [(pentamethylcyclopentadienyl)IrCl(2)(1-benzyl,3-methyl-imidazol-2-ylidene)] was found to depend on the batch of lipase B used. The interaction between the bio- and chemo-catalysts was reduced by employing physical entrapment of the enzyme in silica using a sol-gel process. The nature of the gelation method was found to be important, with an alkaline method preferred, as an acidic method was found to initiate a further side reaction, the acid catalyzed dehydration of the secondary alcohol. The acidic gel was found to be a heterogeneous solid acid.
在手性动态动力学拆分 rac-1-苯乙醇成 R-1-苯乙醇乙酸酯的过程中，我们研究了如何将副反应降到最低。我们改变了有机金属氢转移（消旋化）催化剂，发现这会改变醇氧化形成酮副产物的速率和程度。高活性催化剂[(五甲基环戊二烯基)IrCl(2)(1-苄基，3-甲基-咪唑-2-亚基)]的性能取决于所用脂肪酶 B 的批次。通过使用溶胶-凝胶工艺将酶物理包埋在硅胶中，可以减少生物催化剂和化学催化剂之间的相互作用。凝胶化方法的性质很重要，碱性方法是首选，因为酸性方法会引发进一步的副反应，即酸催化的仲醇脱水。酸性凝胶被发现是一种非均相固体酸。
