Synthesis of 3-Aryl-2-arylamidobenzofurans Based on the Curtius Rearrangement

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• 作者：Amandine Carre虉r ; Jean-Claude Florent ; Emilie Auvrouin ; Patricia Rousselle ; Emmanuel Bertounesque
• 刊名：Journal of Organic Chemistry
• 出版年：2011
• 出版时间：April 15, 2011
• 年：2011
• 卷：76
• 期：8
• 页码：2502-2520
• 全文大小：1435K
• 年卷期：v.76,no.8(April 15, 2011)
• ISSN：1520-6904

文摘

The synthesis of novel 3-aryl-2-arylamidobenzofurans has been accomplished via a Curtius rearrangement strategy in four steps from benzofuran-2-carboxylic acids. The requisite Suzuki鈭扢iyaura cross-coupling, with benzyl 3-bromobenzofuran-2-ylcarbamate or 2-arylamido-3-bromobenzofurans, revealed an unusual reductive debromination process due to the presence of the free NH group. This dehalogenation can be suppressed by N-alkylation. DMAP is an efficient reagent for the one-pot conversion of benzyl benzofuran-2-ylcarbamates into the corresponding benzofuran-2-arylamides through aroylation, thus acting both as an acyl transfer reagent and a deprotecting agent of the Cbz group. A mechanism is postulated.