Lambert Salt-Initiated Development of Friedel–Crafts Reaction on Isatin to Access Distinct Derivatives of Oxindoles

Abstract

Herein, a mild metal-free and efficacious route for the synthesis of biologically important 3-aryl oxindole derivatives is described. Using Lambert salt-initiated hydroarylation of isatin, a diverse array of monoarylated products, symmetrical/unsymmetrical double-arylated products, and deoxygenated hydroarylated products could be synthesized from the single starting substrate in good to excellent yields. A preliminary mechanistic study revealed that the reaction proceeds via a monoarylated product followed by a nucleophilic attack by another electron-rich arene nucleophile under mild conditions. The potential of newly synthesized symmetric/unsymmetric 3,3-disubstituted oxindole, 3-substituted 3-hydroxy oxindoles, 3,3-di­(indolyl)­indolin-2-ones, and α-aryl oxindoles as valuable building blocks is further illustrated.

Development of Transition‐Metal‐Free Lewis Acid‐Initiated Double Arylation of Aldehyde: A Facile Approach Towards the Total Synthesis of Anti‐Breast‐Cancer Agent

“…From our recent findings, [17a] we have established that it is indeed feasible and herein we present an attractive and sustainable alternative method for the synthesis of triarylmethane derivatives using in‐situ generated Lambert salt 1 a .…”

Biocompatible non-leachable antimicrobial polymers with a nonionic hyperbranched backbone and phenolic terminal units

“…68 Phenoxyethanol is also widely used in industry as solvent, synthetic intermediate, and fixing agent for perfumes. 69 Monomer 3 is an AB 2 monomer for acidcatalysed Friedel-Crafts type polymerizations (the phenyl group can react twice with the carbonyl group in each monomer), [70][71][72] which can yield a non-crosslinked hyperbranched polymer structure with diaryloxindoles backbone. 73,74 AB 2 monomer 3 was polymerized according to a previously reported polymerization protocol for a similar monomer, 63 which was performed at room temperature without solvent, yielding the desired isatin-based precursor HBP1 after a simple precipitation from methanol.…”

Lewis Acid Promoted Homodimerization of Styrene Diols: An Efficient Approach toward 2-Phenylnaphthalenes

“…After the activation of the aldehyde by the Lewis acid, the electron-rich additive, 1,3-dimethoxybenzene, attacks as a nucleophile to produce the monoarylated product B . 15a b Next, abstraction of a proton by the triflate ion generates alkene C in situ in the reaction medium. Alkene C is converted into the cationic intermediate D under the acidic conditions, as proposed by ­Vishwakarma and Bharate and their co-workers.…”