A multifunctionalized strategy of indoles to C2-quaternary indolin-3-ones via a TEMPO/Pd-catalyzed cascade process

Abstract

A method for combinative oxidative homo dimerization and cyanomethylation of free indole derivatives catalysed by TEMPO and Pd(OAc) was demonstrated for the first time. This new methodology is both atom and step efficient and is applicable to a broad scope of substrates, allowing the synthesis of a range of synthetically valuable 2-(2-(1H-indol-3-yl)-3-oxoindolin-2-yl)acetonitriles in moderate to excellent yields.

Oxidative Dearomative Cross-Dehydrogenative Coupling of Indoles with Diverse C-H Nucleophiles: Efficient Approach to 2,2-Disubstituted Indolin-3-ones

“…Notably, decreasing the amount of Cu(OTf)2 to 0.005 equivalent had no effect on the reactivity of the reaction (Table 1, entry 10). Moreover, under the optimized conditions, the dimer 6a was obtained in 98% reactions focus on the construction of di-or trimerization of indoles [50,[77][78][79][80], and the reactions of indoles with dissimilar C-H nucleophiles are considerably rare [81][82][83]. Recently, we reported an efficient oxidative dearomatization reaction of indoles [84,85].…”

Aerobic Oxidative Functionalization of Indoles

“…In this regard, Liu et al revealed that acetonitrile was smoothly coupled via a TEMPO/Pdcatalyzed cascade process. [123] Notably, halogen functionalities including fluoro, chloro, and bromo were compatible with this palladium catalysis. The same group also explored TMSCN as a cyanating reagent for the similar cascade oxygenation, in which a palladium-free catalytic system was found to be effective (Scheme 54).…”

Pd‐Catalyzed One‐Pot Insertion Reaction of Cyclic C‐Acylimines into Carbon‐Carbon σ‐Bonds for the Synthesis of Polyfunctional Indolin‐3‐ones from 2‐Alkynyl Arylazides and Aryl Ketones

“…Indolin‐3‐ones are versatile synthetic building blocks and utilizedas core structures in thepreparation of various naturalproducts, such as austamide, halichrome A , cephalinone, andfluorocurine . Especially, polyfunctional indolidin‐3‐ones areof considerable useful intermediates for the construction of natural products…”