Palladium‐Catalyzed Direct Oxidative Esterification of Indoles at the C3 Position: A Novel Prospect for C(sp²)−H Acyloxylation

Abstract

An efficient palladium‐catalyzed direct oxidative esterification reaction of indoles with both aliphatic and aromatic carboxylic acids is reported. The use of Ag2CO3 is crucial to this transformation, as it functions as both a base and an oxidant for the regeneration of the palladium(II) catalyst. This methodology represents a novel prospect for C(sp2)−H acyloxylation and will promote interest in direct C(sp2)−H esterification.

Pd‐Catalyzed Tandem Coupling Reaction of 2‐gem‐Dibromovinylanilines and N‐Tosylhydrazones to Construct 2‐(1‐phenylvinyl)‐indoles

“…On the basis of pioneering study and our work in developing new methodologies to functionalized indoles, we disclose a palladium(0)‐catalyzed alkenylation of indoles at the C2‐position from 2‐ gem‐ dibromovinylanilines and hydrazones, during which indole ring bearing 1,1‐disubstituted alkenes were obtained in one step (Scheme f).…”

Recent Advances of Cinnamic Acids in Organic Synthesis

“…Directed C−H functionalization of arenes has proven to be a reliable and powerful approach. The Scheme is providing an overview of the use of cinnamic acids as reactants in C sp2 −H activation of indoles, 2‐substituted1,2,3‐triazoles, 2‐phenylpyridine, N ‐aryl‐2‐pyrimidines, quinolones and coumarins . In the presence of Pd, Rh Ru or Cu‐catalyst, the directing 1,2,3‐triazole, pyrimidine, pyrimidines or 1,3,5‐triazine acted as a coordinating group to achieve protocols for esterification (Scheme ).…”

Arylacetic Acids in Organic Synthesis

“…The results of these reactions included direct ortho ‐acyloxylation of 2‐functional arenes, benzylation with toluene, and cross‐coupling of aromatic compounds via C−H bond activation . An oxidant and heating condition were required, while the Pd(OAc) 2 – was mostly employed as the metal‐catalyst.…”