[5C + 1N] Annulations: Two Novel Routes to Substituted Dihydrofuro[3,2-c]pyridines

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• 作者：Peng Huang ; Rui Zhang ; Yongjiu Liang ; Dewen Dong
• 刊名：Organic Letters
• 出版年：2012
• 出版时间：October 19, 2012
• 年：2012
• 卷：14
• 期：20
• 页码：5196-5199
• 全文大小：217K
• 年卷期：v.14,no.20(October 19, 2012)
• ISSN：1523-7052

文摘

Two novel routes based on [5C + 1N] annulations for the synthesis of 2,3-dihydrofuro[3,2-c]pyridines are described. Ammonium acetate (NH₄OAc) is used as an ammonia source in both routes. The first route utilizes 1-acyl-1-[(dimethylamino)alkenoyl]cyclopropanes as a five-carbon 1,5-bielectrophilic species and combines the [5C + 1N] annulation and regioselective ring-enlargement of cyclopropyl ketone into one pot, whereas the second route utilizes 3-acyl-2-[(dimethylamino)alkenyl]-4,5-dihydrofurans as the five-carbon synthons, which involves a sequential intermolecular aza-addition, intramolecular aza-nucleophilic addition/elimination, and dehydration reaction.