Synthesis And Chiral Separation Of Chiral Spiro-Compounds

Recently, synthesis of chiral compounds has attracted a great deal of interests due to itspotential application in asymmetric catalytic reaction. Under many circumstance enantiomersof pharmaceutical compounds may display quite different pharmacological behaviors. Sometimes, they may even have opposite properties as medicine. With the development of scienceand technology, people deeply realize the distinguish between enantiomers for optically activecompounds. It is becoming important to separate optical active compounds in the fields ofbiochemistry, organic chemistry, pharmaceutical chemistry as well as asymmetric synthesisand catalysis. Now enantioseparation by highperformance liquid chromatography (HPLC) ona chiral stationary phase has become an increasingly practical and effective method to obtainoptical isomers and determine purity. The method was often used in medicine, pesticides andasymmetric catalysis. There are various types of CSPs available. Among the various CSPs,cellulose-andamylose-based CSPs have been proved to be quite versatile by Okamoto et al. Itwas demostrated that the amylose tris-(3,5-dimethylphenylcarbamate) and cellulose tris-(4-methylbenzoate) were particularly effective.In this paper, two spiro compounds of 3,9-diphenyl-2,4,8,10-tetraoxaspiro[5.5]–undecane and 3,9-di(4-formyl-phenyl)-2,4,8,10-tetraoxaspiro[5.5]-undecane wereprepared by pentaerythritol reacting with benzaldehyde or phthalaldehyde mono-acetal inpresence of HCl. The direct enantiomeric separation of two dl-compounds has firstly beenachieved using n-hexane as the mobile phase with iso-propanol on derivatized amylose andcellulose chiral stationary phases (Chiralpak AD-H and Chiralpak OJ-H).The effect of mobilephase modifiers on a compound's retention factor(K') and resolutions (Rs) were investigated,and chromatographic conditions were optimized.The results showed that a low percentage ofiso-propanol provided best separation.It can be seen that separation factor is largest whenhexane to iso-propanol is 98:2 as mobile phase,and chromatographic conditions wereoptimized. The isolation of individual enantiomers were achieved and the optical rotation forthe isolated enantiomers was measured. The configuration s for the enantiomers wereinterpreted by Lowe's rule based on their structure and optical properties .Secondly, the dendrimer being introduced in this paper was successfully synthesize dwhich gives a big contribute to the basic work of synthesizing the chiral catalyst, and it isuseful to the partner of research team as the basic work.Finally, base on reading many literature , the new method to synthesize the Fecht acidwas investigated and discussed.