Premium
From Benzofurans to Indoles: Palladium‐Catalyzed Reductive Ring‐Opening and Closure via β‐Phenoxide Elimination
Author(s) -
Perego Luca A.,
Wagschal Simon,
Grüber Raymond,
FleuratLessard Paul,
El Kaïm Laurent,
Grimaud Laurence
Publication year - 2019
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201801225
Subject(s) - benzofuran , palladium , chemistry , reductive elimination , ring (chemistry) , catalysis , medicinal chemistry , indole test , combinatorial chemistry , stereochemistry , organic chemistry
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 by an uncommon trans ‐elimination of the phenoxide group β to the metal. In this transformation, N , N ‐diisopropylethylamine (DIPEA) acts as a base and as a reducing agent: it regenerates palladium(0) from palladium(II), thus allowing catalytic turnover.