Protecting Group‐Free Gold‐Catalyzed Synthesis of 2‐Acylidene‐3‐Oxindoles and Azaaurones via a Double Oxidation Strategy

Abstract

A one‐pot synthesis of 2‐acylidene‐3‐oxindole and azaaurone derivatives starting from O‐alkynylanilines and alkynes is presented. By means of oxidative gold catalysis the two starting materials are transferred to reactive intermediates that in situ form the target products. This double oxidation strategy enables a protecting group‐free step‐economic strategy towards these valuable substrate classes.

Scaffold-Hopping Strategies in Aurone Optimization: A Comprehensive Review of Synthetic Procedures and Biological Activities of Nitrogen and Sulfur Analogues

“…Alternatively, Methods V and VI involve a one-pot gold-catalyzed protocol. In the former, the reaction between O-alkynylaniline 9 and aromatic aldehyde affords the title azaaurone scaffold through a protection-group-free double oxidation strategy in the presence of activated phosphane gold complexes as a catalyst (JohnPhosAuCl/AgNTf 2 ) and 8-methylquinoline N-oxide as an oxidizing agent [ 30 ].…”

“…More limited applications and fewer substituents explored. [30,31] On the other hand, the recently proposed protocols IV-VI give the opportunity of a one-pot coordinated synthesis by exploiting a finer transition organometallic catalysis. Such an approach undoubtedly has a positive impact on the overall yield and reaction times.…”

“…[ 30,31] 2.1.2. Synthetic Procedures: Scaffold Elaboration By exploiting the high versatility of these compounds, other interesting synthetic methods for modifying the azaaurone scaffold have been reported in the literature, providing interesting building blocks for the identification of new biologically active derivatives and further alternatives for SAR exploration.…”

Oxidative Transformation of 2-Furylanilines into Indolin-3-ones

“…Up until now, no systematic research has been attempted in order to define the chemoselectivity, generality, and synthetic utility of a potential transformation that could in principle provide a convenient disconnection for targeting functionalized aza-heterocycles . In the current study, we aim to fill the potential methodological gap by demonstrating that the oxidation of 2-furylanilines, the accessible representatives of the latter class of furyl amines, yields valuable indoline-3-ones , as well as their unsaturated analogues , via the formation of N–C(3) furan bonds with a general character (Figure c).…”