有机化学 ›› 2018, Vol. 38 ›› Issue (6): 1525-1529.DOI: 10.6023/cjoc201712020 上一篇    下一篇

研究论文

应用苄位C—H氟化形式合成α,β-二氟代-γ-氨基酸

刘清泉, 胡祥国   

  1. 江西师范大学国家单糖化学合成工程技术研究中心 南昌 330022
  • 收稿日期:2017-12-13 修回日期:2018-01-19 发布日期:2018-02-06
  • 通讯作者: 胡祥国,E-mail:huxiangg@iccas.ac.cn E-mail:huxiangg@iccas.ac.cn
  • 基金资助:

    国家自然科学基金(No.21502076)、江西省杰出青年资助计划(No.20171BCB23039).

Application of Benzylic C-H Fluorination for the Formal Synthesis of syn-α, β-Difluoro-γ-amino Acid

Liu Qingquan, Hu Xiangguo   

  1. National Engineering Research Center for Carbohydrate Synthesis, Jiangxi Normal University, Nanchang 330022
  • Received:2017-12-13 Revised:2018-01-19 Published:2018-02-06
  • Contact: 10.6023/cjoc201712020 E-mail:huxiangg@iccas.ac.cn
  • Supported by:

    Project supported by the National Natural Science Foundation of China (No. 21502076) and the Outstanding Young Talents Scheme of Jiangxi Province (No. 20171BCB23039).

苄位C—H氟化已经成为一种向分子内引入氟原子的重要手段,然而,苄位C—H氟化反应还没有被应用到任何多步合成中.由于氟的构象效应,αβ-二氟代-γ-氨基酸在生物化学中有着重要的应用,但是其合成却具有一定的挑战性.在本文中,苄基C—H氟化作为关键步骤被成功用于syn-αβ-二氟代-γ-氨基酸1的形式合成.基于以下原因,本工作的合成路线比文献中的路线更为实用:(1)没有使用具有腐蚀性和毒性的亲核氟代试剂;(2)总收率为18%(以前的方法约为5%);(3)关键苄位C—H反应被放大到了克量级.在对反应进行优化的过程中,观察到明显的氟效应,即对于苄位C—H氟化反应,邻位含有氟原子的碳比普通碳反应活性低很多.

关键词: C-H氟化, 有机氟, 氨基酸

Benzylic C-H fluorination has emerged as a valuable tool for the introduction of fluorine. However, the powerfulness of benzylic C-H fluorination has not been tested in any multi-step synthesis. α,β-Difluoro-γ-amino acids are useful entities for biological application owing to the so-called fluorine conformational effect. In this work, benzylic C-H fluorination has been successfully utilized as the key step for the formal synthesis of syn-α,β-difluoro-γ-amino acid 1, a very challenging but useful target. The approach developed in this work could be viewed as more practical compared to the previous one, because:(1) no corrosive and toxic nucleophilic fluorinating reagents are used, (2) the overall yield is 18% (the previous approach is about 5%), and (3) the key benzylic C-H reaction developed by Chen and co-workers was scaled up to one gram without decreasing its original efficiency. A striking fluorine effect was observed:a carbon with one fluorine atom on the adjacent carbon is much less reactive than an ordinary carbon for the benzylic C-H fluorination.

Key words: C-H fluorination, organofluorine, amino acid