CNRS UMR 176, 26 rue d'Ulm, 75248 Paris, France.
J Org Chem. 2011 Apr 15;76(8):2502-20. doi: 10.1021/jo102265b. Epub 2011 Mar 10.
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-Miyaura 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.
新型 3-芳基-2-芳酰胺苯并呋喃的合成为通过从苯并呋喃-2-羧酸的Curtius 重排策略在四步中完成。必要的Suzuki-Miyaura 交叉偶联反应，使用苄基 3-溴苯并呋喃-2-基氨基甲酸酯或 2-芳基酰胺-3-溴苯并呋喃，由于存在游离的 NH 基团，显示出不寻常的还原脱溴过程。通过 N-烷基化可以抑制这种脱卤。DMAP 是一种有效的试剂，可通过芳基化将苄基苯并呋喃-2-基氨基甲酸酯一锅转化为相应的苯并呋喃-2-芳酰胺，从而既作为酰基转移试剂，又作为 Cbz 基团的脱保护剂。提出了一种机制。
