Direct cyclization of ortho-(1H-pyrrol-1-yl)aryl and heteroaryl carboxylic acids into fused pyrrolizinones
摘要:
A series of fused heterocyclic compounds based on a pyrrolizinone structure have been prepared from ortho-(1H-pyrrol-1-yl)aryl and heteroaryl carboxylic acids by intramolecular Friedel-Crafts acylation promoted by bis(trichloromethyl) carbonate, in generally good yield without using Lewis acid catalysts. (C) 2010 Elsevier Ltd. All rights reserved.
the high functional group tolerance of this transformation. In addition, study of the reaction mechanism is also presented to unfold the exact role of the applied base additive. Herein, as a first example, we report our findings that Tf2O-mediated amide activation is obstructed by the easy protonation of amides by the formed triflic acid during the activation step. Additionally, it has been also proven
已开发出一种有效的合成方法,可通过一锅酰胺和吡咯形成步骤,从容易获得的邻氨基苯甲酸衍生物制备9 H-吡咯并[1,2 - a ]吲哚-9-酮(氟唑酮)分子内环脱水 环脱水过程是由三氟甲磺酸酐(Tf 2 O)活化芳族叔酰胺介导的。各种苯并取代基的比较显示出证明了这种转化的高官能团耐受性。此外,还对反应机理进行了研究,以揭示所用基础添加剂的确切作用。在此,作为第一个示例,我们报告我们的发现,即Tf 2在活化步骤中,形成的三氟甲磺酸使酰胺易于质子化,从而阻碍了O介导的酰胺活化。另外,还已经证明,该碱添加剂不参与将O-三氟甲磺酸三氟甲磺酸盐转化成反应性物种(例如,三氟甲磺酸腈),并且仅负责中和超酸以避免仲酰胺或叔酰胺的质子化。 。
Direct cyclization of ortho-(1H-pyrrol-1-yl)aryl and heteroaryl carboxylic acids into fused pyrrolizinones
作者:Francesca Aiello、Antonio Garofalo、Fedora Grande
DOI:10.1016/j.tetlet.2010.10.060
日期:2010.12
A series of fused heterocyclic compounds based on a pyrrolizinone structure have been prepared from ortho-(1H-pyrrol-1-yl)aryl and heteroaryl carboxylic acids by intramolecular Friedel-Crafts acylation promoted by bis(trichloromethyl) carbonate, in generally good yield without using Lewis acid catalysts. (C) 2010 Elsevier Ltd. All rights reserved.