Third-Liquid Phase Transfer Catalysis for Horner–Wadsworth–Emmons Reactions of “Moderately Acidic” and “Weakly Acidic” Phosphonates

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• 作者：Qiangqiang Zhao ; Lei Yang ; Yifeng Shen
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2016
• 出版时间：July 20, 2016
• 年：2016
• 卷：55
• 期：28
• 页码：7604-7611
• 全文大小：413K
• 年卷期：0
• ISSN：1520-5045

文摘

The Horner–Wadsworth–Emmons (HWE) reaction was investigated in a green third-liquid phase-transfer catalysis (TLPTC) system. With 6% equiv of the catalyst and 50% NaOH aqueous solution, the third phase was generated. In this TLPTC system, HWE reactions of benzaldehydes bearing an electron-donating group with “weakly” or “moderately” acidic phosphonates proceeded in high yield (>90%) with an all E-isomer product (stilbene). Teraoctyl ammonium bromide (TOAB) afforded a high yield of 93% for the HWE reaction of benzaldehydes with electron-withdrawing groups. It was found that the ratio of E-stilbene to Z-stilbene was also influenced by the steric hindrance of the achiral quaternary ammonium salt catalyst. The isolated yield and geometric selectivity for the HWE reaction remained unchanged in four consecutive runs of both the third and the aqueous phase. A highly efficient and practical hydroxide-initiated TLPTC system was developed for the HWE reaction.