Study On Kinetic Resolution Of α-Fluoro Secondary Alcohols And Research On The Suzuki Reaction Conditions Of Cyanohydrins

Enantiomerically pure cyanohydrins and fluorinated secondary alcohols are important c hiral intermediates in organic synthesis.They therefore provide a wide space for transform ation into a large number of chiral molecules,which are important in the synthesis of bio logically active molecules.In this dissertation a study on the synthesis ofα-substitued 2,2-difluoro -3-hydroxy-3-aryl-propionates and 2,2,2-trifluoro-1-aryl ethanol from commercial a vailable materials was made for the later kinetic resolution with enzymes.Through investigation on the influence of the composition of mobile phase,the flow rate, the injected concentration on the enantiomer rententivity and selectivity and column temperature on the chiral separation,the chromatographic conditions were optimized.When we synthesis eantiomerically pure cyanohydrins,we find that when eantiomerically pure cyanohydrins have huge hinded groups.For example,enzymatic kinetic resolution of some other secondary alcohols containing electron withdrawing groups gave poor enantioselectivity by nonenzymatic kinetic resolution,we can not get them with good ee vales.We attempt to develop a better method for the preparation of those compounds.And we use Suzuki reaction to try to solve the problem.First we use serval commercial available materials to produce cyanohydrins containing halogen.The racemic cyanohydrins were then esterified with acetic anhydride and then the products were combined with the Suzuki reaction.When we tried to make the reaction take place in a common Suzuki reaction condition (＞50℃),we found that the esterified cyanohydrins would be decomposed,and by the way of TLC, the primary aldehyde was found.Serval mild conditions were used to make the Suzuki reaction take place but we failed.