W（OTf）6-催化大环内酯的环收缩或末端羟基脂肪酸在离子液体中的闭环合成γ-内酯,ChemSusChem

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W（OTf）6-催化大环内酯的环收缩或末端羟基脂肪酸在离子液体中的闭环合成γ-内酯
ChemSusChem ( IF 7.5 ) Pub Date : 2018-06-21 , DOI: 10.1002/cssc.201800587
Zhong-Yu Xie _{1,

2} , Jin Deng ₁ , Yao Fu ₁

Affiliation

γ-内酯是一类重要的精细化工产品，广泛用于香水，药品，农药，染料和其他领域。本文提出了一种基于环收缩的γ-内酯制备新方法。从大环内酯类化合物开始，使用W（OTf）₆催化开环聚合然后解聚。解聚步骤不是通常的闭环过程，通过重新排列形成最热力学上稳定的五元环化合物，环的碳数被一一减少。当使用[EMIM] OTf作为溶剂时，可得到94％的γ-己内酯（180°C，10小时），分离产物的产率高达85％。用FTIR光谱研究了各种组分的相互作用和反应机理。¹ H NMR光谱分别。此外，当底物延伸至末端羟基脂肪酸时，可能会生成γ-内酯。出乎意料的是，在此过程中，催化剂会因加入1当量的H ₂ O而中毒，因此收率大大降低。该反应是绿色且简单的，并且在一个具有高原子经济性的锅中进行（大环内酯类化合物为100％，水为末端羟基脂肪酸的唯一副产物），这为合成γ-内酯提供了一种有前途的方法。

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W(OTf)6‐Catalyzed Synthesis of γ‐Lactones by Ring Contraction of Macrolides or Ring Closing of Terminal Hydroxyfatty Acids in Ionic Liquid

γ‐Lactones are an important class of fine chemical products and are widely used in perfumes, medicines, pesticides, dyes, and other fields. Herein, a new method for γ‐lactones preparation based on ring contraction was developed. Starting from macrolides, W(OTf)₆ was used to catalyze the ring‐opening polymerization then depolymerization. The depolymerization step was not a common ring‐closing process, and the carbon number of the ring was reduced one by one by rearrangement to form the most thermodynamically stable five‐membered ring compounds. γ‐Caprolactone (180 °C for 10 h) was obtained in a yield of 94 % when [EMIM]OTf was used as the solvent, and the yield of isolated product was up to 85 %. The interaction of various components and the reaction mechanism were studied by FTIR spectroscopy and ¹H NMR spectroscopy, respectively. Furthermore, γ‐lactones could be produced when the substrate was extended to terminal hydroxyfatty acids. Unexpectedly, the catalyst was poisoned by 1 equivalent of H₂O added during the process and thus the yield decreased greatly. The reaction is green and simple, and proceeds in one pot with high atom economy (100 % for macrolides and with water as the only byproduct for terminal hydroxyfatty acid), which provides a promising approach to synthesizing γ‐lactones.

更新日期：2018-06-21

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