The Study Of Alkylation By Using Benzimidazole Derivatives As Chiral Ligands

Benzimidazole is a cheap, readily available heterocyclic compound. By the modification and functionalization at N-1and C-2, various of benzimidazole derivatives could be obtained. Benzimidazole and its derivatives are still fresh used as chiral auxiliaries and ligands in asymmetric synthesis. In this study, benzimidazole-pyrrolidine derivatives was used as chiral auxiliaries. Through the type of metal coordination chiral transfer, the asymmetric a-alkylation of carbonyl compounds is happened. This paper includes three chapters.Chapter one, review:the research on a-alkylation of carbonyl compounds is introduced in brief, and then the enol’s design of the chiral compound, the chiral transfer, the separation of the enantiomer and the synthesis of the benzimidazole and its derivatives are reviewed in this part. After that the theme of this paper is proposed.Chapter two, experiment:O-phenylenediamine and L-proline are used as raw materials to generate2-substituted benzimidazole in acidic conditions. Then the secondary amine in the pyrrolidine ring is acylated by butyric anhydride; Lastly, with the help of alkali LDA, a-carbon asymmetric alkylation reaction is carried out. The effect of benzimidazole-pyrrolidine derivatives as chiral auxiliaries is investigated, and. the characteristic in the a-alkylation of benzimidazole derivatives is concluded.Chapter three, results and discussion:reaction mechanisms of important steps in the synthetic route are explained, problems and notes during the synthetic process and asymmetric alkylation are discussed. In addition, some other test methods using in the synthesis of target compounds are introduced and analyzed.