From Benzofurans to Indoles: Palladium‐Catalyzed Reductive Ring‐Opening and Closure
<i>via</i>
β‐Phenoxide Elimination
作者:Luca A. Perego、Simon Wagschal、Raymond Grüber、Paul Fleurat‐Lessard、Laurent El Kaïm、Laurence Grimaud
DOI:10.1002/adsc.201801225
日期:2019.1.11
Benzofurans can undergo ring‐opening by a palladium‐catalyzed process resulting in C−O bond breaking. Benzofuran‐tethered 2‐iodoanilines give synthetically interesting 2‐(3‐indolylmethyl)phenols in an overall reductive process. Mechanistic studies suggest that this unusual reaction proceeds by carbopalladation of benzofuran giving a 3‐palladated 2,3‐dihydrobenzofuran intermediate, which then fragments
苯并呋喃可以通过钯催化的过程进行开环,从而导致C-O键断裂。在整个还原过程中,苯并呋喃拴系的2-碘苯胺可合成有趣的2-(3-吲哚基甲基)苯酚。机理研究表明,这种不寻常的反应是通过苯并呋喃的碳钯反应生成的,这是一种3-palladed的2,3-二氢苯并呋喃中间体,然后通过苯氧根β的不常见反式消除作用而分裂成金属。在此转化过程中,N,N-二异丙基乙胺(DIPEA)充当碱和还原剂:它从钯(II)再生钯(0),从而实现催化转化。