Synthesis of Polysubstituted Furans Based on a Stepwise Sonogashira Coupling of (Z)-3-Iodoalk-2-en-1-ols with Terminal Propargylic Alcohols and Subsequent Au(I)- or Pd(II)-Catalyzed Cyclization−

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• 作者：Xiaobing Zhang ; Zhan Lu ; Chunling Fu ; Shengming Ma
• 刊名：Journal of Organic Chemistry
• 出版年：2010
• 出版时间：April 16, 2010
• 年：2010
• 卷：75
• 期：8
• 页码：2589-2598
• 全文大小：973K
• 年卷期：v.75,no.8(April 16, 2010)
• ISSN：1520-6904

文摘

Recently, we have developed highly regio- and stereoselective carbometalation of 2-alkynols and 2,3-allenols. The organometallacyclic intermediates may be trapped with I₂ to afford 3-iodoalk-2-en-1-ols. These 3-iodoalk-2-en-1-ols may readily undergo the Sonogashira coupling with terminal propargyl alcohols to form 4-alkyn-2-ene-1,6-diols. Subsequent cycloisomerization in DMA or CH₂Cl₂ with Au(PPh₃)Cl and AgOTf as the catalyst would afford polysubstituted 2-(1-alkenyl)furans; with PdCl₂ as the catalyst and the reaction in DMA in the presence of allylic bromides, the same substrates afforded polysubstituted 2-(1,4-alkadienyl)furans. In both types of catalyzed cyclization reactions, the elimination of H₂O promoted the aromatization to form the furan ring. Different alkyl or aryl groups could be introduced into different positions of furans due to the substituent-loading capability of 3-iodoalkenols and diversity of the terminal propargyl alcohols and allylic bromides.