One-Pot Novel Regioselective Cycloisomerization Synthesis of 2-Substituted or 3-Substituted 4H-Furo[3,2-c]chromene through the Intermediate Cyclopropenes of 3-Diazochroman-4-one and Phen

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• 作者：Jin Gong ; Zhensheng Zhao ; Fuming Zhang ; Songyun Wu ; Guangqi Yan ; Yingjie Quan ; Baochun Ma
• 刊名：Organic Letters
• 出版年：2014
• 出版时间：November 7, 2014
• 年：2014
• 卷：16
• 期：21
• 页码：5524-5527
• 全文大小：379K
• ISSN：1523-7052

文摘

A new class of cyclopropenes containing a chroman-4-one motif were synthesized using 3-diazochroman-4-one and phenylacetylene with rhodium(II) catalyst and followed by cycloisomerization to give 2-substituted or 3-substituted 4H-furo[3,2-c]chromene, respectively. Using BF₃路Et₂O as catalyst, 2-substituted 4H-furo[3,2-c]chromene was exclusively obtained in 70% yield. Using Cu(OTf)₂ as catalyst, 3-substituted 4H-furo[3,2-c]chromene was obtained in 95% yield with 98:2 regioselectivity. A one-pot cascade addition鈥揷ycloisomerization process was also developed with no need to isolate cyclopropenes of chroman-4-one intermediates.