The [2 + 2] Cycloaddition鈥揜etroelectrocyclization and [4 + 2] Hetero-Diels鈥揂lder Reactions of 2-(Dicyanomethylene)indan-1,3-dione with Electron-Rich Alkynes: Influence of Lewis Acids on Reactivity

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• 作者：Etienne J. Donckele ; Aaron D. Finke ; Laurent Ruhlmann ; Corinne Boudon ; Nils Trapp ; Fran莽ois Diederich
• 刊名：Organic Letters
• 出版年：2015
• 出版时间：July 17, 2015
• 年：2015
• 卷：17
• 期：14
• 页码：3506-3509
• 全文大小：334K
• ISSN：1523-7052

文摘

The reaction of electrophilic 2-(dicyanomethylene)indan-1,3-dione (DCID) with substituted, electron-rich alkynes provides two classes of push鈥損ull chromophores with interesting optoelectronic properties. The formal [2 + 2] cycloaddition鈥搑etroelectrocyclization reaction at the exocyclic double bond of DCID gives cyanobuta-1,3-dienes, and the formal [4 + 2] hetero-Diels鈥揂lder (HDA) reaction at an enone moiety of DCID generates fused 4H-pyran heterocycles. Both products can be obtained in good yield and excellent selectivity by carefully tuning the reaction conditions; in particular, the use of Lewis acids dramatically enhances formation of the HDA adduct.