A Novel and Chemoselective Process ofN-Alkylation of Aromatic Nitrogen Compounds Using Quaternary Ammonium Salts as Starting Material

Carlos A. González-González,Aydeé Fuentes-Benítes,Davir González-Calderón,David Corona-Becerril,Joaquín Tamariz Mascarúa,Juan Javier Mejía Vega,Ricardo García Monroy,Carlos González-Romero

doi:10.1155/2017/4586463

Carlos A. González-González, Aydeé Fuentes-Benítes + Show 6 more

Open Access

https://doi.org/10.1155/2017/4586463

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Abstract

The process ofN-alkylation of several pyrroles, indoles, and derivative heterocycles is herein described, using quaternary ammonium salts as the source of an alkylating agent. These reactions were carried out on several heterocyclic rings with triethylbenzylammonium chloride or tetradecyltrimethylammonium bromide and an NaOH solution at 50%, leading to a chemoselectiveN-alkylated product and an average yield of 73%. This is an alternative process to the traditional benzylation and methylation ofN-heterocycles with direct handling of alkyl halides.

Highlights

Quaternary ammonium salts are one of the most widely used reagents in the synthesis of organic compounds when seeking to develop certain vital products, including drugs, pesticides, monomers, and cleaning agents [1, 2]
We discovered that if the original alkylating agent was omitted from the reaction, employing instead more than a stoichiometric amount of triethylbenzylammonium chloride (TEBAC), a clean transfer of a unique benzyl group took place
A predictably poor alkylating agent, isopropyl iodide, gave only N-isopropyl-2-phenylindole in low yield when a normal quantity (25% mole) of TEBAC was used in conjunction with 1 eq of alkylating agent

Summary

Introduction

Quaternary ammonium salts are one of the most widely used reagents in the synthesis of organic compounds when seeking to develop certain vital products, including drugs, pesticides, monomers, and cleaning agents [1, 2]. In the area of materials development, they have been employed in recent years as surfactants, template agents, and alkaline anion exchange membranes (AAEM) [3, 4]. In organic chemistry, these salts have various applications in situations where inorganic and organic anions react with organic substrates that are separated into distinct phases known as phase-transfer catalysis. These salts have various applications in situations where inorganic and organic anions react with organic substrates that are separated into distinct phases known as phase-transfer catalysis These anions need to be introduced in the organic phase as a lipophilic ion pair provided by a catalyst. There are a variety of articles about phase-transfer catalysts, little has been reported about them as an alkylating agent of nitrogen heterocyclic rings [5]

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