对称降冰片二烯二羧酸二酯的高选择性单水解

Highly Selective Monohydrolysis of Symmetrical Norbornadiene Dicarboxylate

半酯是有机合成中非常重要的中间体,大体积对称二酯的选择性单水解高产率制备半酯的研究具有重要意义。本研究采用THF、DMSO、CH3CN作为共溶剂,在0℃碱溶液中将对称结构的降冰片二烯衍生物进行选择性单水解反应,考察了三种共溶剂比例、不同碱及碱的用量对水解反应的影响。结果表明,当共溶剂与H2O体积比为1∶10的情况下,THF、DMSO、CH3CN作为共溶剂时对甲基酯的选择性和活性都很高,都能够极大地改善水解反应,在反应30~45 min条件下,产率>99%。在LiOH、NaOH、KOH、CsOH四种不同的碱中,KOH的水解反应活性最好,但是,其对反应活性的提高是有限的。同时,共溶剂/碱体系受酯基疏水性的影响较大,本研究探讨了二酯疏水性在不同共溶剂体系下对单水解的影响,结果表明,在DMSO作为共溶剂时,疏水性增强的对称二酯具有很高的反应活性和水解选择性。该研究为半酯的合成提供了重要的方法学依据。

Half ester is an important intermediate in organic synthesis and it is of great significance to study the selective monohydrolysis of bulky symmetric diesters to prepare half ester with high yield.In this work,THF,DMSO and CH3 CN as co-solvent were used to carry out selective monohydrolysis of symmetrical norbornadiene dicarboxylate under the temperture of 0℃in aqueous alkali.Effects of the ratio of co-solvent and the different alkali on hydrolysis reactions were investigated.The results proved that the selectivity and activity of monohydrolysis were very high when the ratio of co-solvent and H2 O was 1:10.This reaction conditons can greatly improve monohydrolysis,which promoted the selectivity and reactivity under the reaction time of 30~45 min and obtained half ester with high yield(>99%).KOH had the best hydrolysis activity among LiOH,NaOH,KOH and CsOH,but it had insignificant influence on reaction activity.Meanwhile,the co-solvent/base system was greatly affected by the hydrophobicity of ester group.In this paper,the effect of the hydrophobicity of diesters on the monohydrolysis in different co-solvent was explored.The results showed that the high activity and selectivity of monohydrolysis of hydrophobic diesters can be maintained using DMSO as co-solvent.This study provides an important method for the synthesis of half ester.