高等学校化学学报

高等学校化学学报

• 研究论文 • 上一篇    下一篇

脂肪族酯基选择性还原模型的建立

吕晓洁1,2, 蒋举兴1,2, 任洁1, 朱华结1   

    1. 中国科学院昆明植物研究所植物化学与西部植物资源持续利用国家重点实验室, 有机合成与天然产物实验室, 昆明 650204;
    2. 中国科学院研究生院, 北京 100039
  • 收稿日期:2007-05-09 修回日期:1900-01-01 出版日期:2008-03-10 发布日期:2008-03-10
  • 通讯作者: 朱华结

Chemoselective Reduction Model of Aliphatic Esters with Sodium Borohydride

LÜ Xiao-Jie1,2, JIANG Ju-Xing1,2, REN Jie1, ZHU Hua-Jie1*   

    1. Organic Synthesis and Natural Product Laboratory, State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, China;
    2. Graduate School of the Chinese Academy of Sciences, Beijing 100039, China
  • Received:2007-05-09 Revised:1900-01-01 Online:2008-03-10 Published:2008-03-10
  • Contact: ZHU Hua-Jie

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摘要： 以不同烷基取代的酯作为模型, 对其进行NaBH4还原研究. 不同取代基酯的起始反应温度和半衰期显示出了明显的差别和一定的选择性; 用B3LYP/6-31++G(d,p)//HF/6-31G(d,p)方法计算得到的过渡态能量与实验得到的活化能变化趋势一致; 实验中观察到了奇偶碳效应; 对NaBH4还原酯基的溶剂影响进行了初步研究.

关键词: 脂肪族酯, 选择性还原反应, 过渡态能量, 半衰期, 奇偶碳效应

Abstract: Sodium borohydride has been widely used in different organic reductions due to its moderate chemical activity. The reductions of ester with sodium borohydride could produce various alcohols as intermediates for further reactions. The esters with different alkyl substituents are used as the models in sodium borohydride reductions, and on-set temperatures, half-life periods and transition state(TS) energies were obtained experimentally. Some of the TS energetics were computed using B3LYP/6-31++G(d,p)//HF/6-31G(d,p) method. The differences of on-set temperatures among these esters were substantial and some observed selectivities were obtained when the aliphatic substituents changed from Me, Et, n-Pr to n-Bu. Odd-even carbon effect, which was first mentioned in our previous report in enantioselective additions of diethylzinc to benzaldehyde, was observed again in the reductions. Traditionally, organic theory uses the size of the substitutents to explain the reaction TS energy order. However, the traditional theory can not be used to explain the observed odd-even carbon effect. The reason for this effect happened in different reactions is still unknown. Furthermore, the effect of solvent in the reductions was investigated primarily.

Key words: Aliphatic esters, Chemoselective reduction, Transition state energy, Half-life period, Odd-even carbon effect

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