Synthesis 2017; 49(16): 3535-3545
DOI: 10.1055/s-0036-1588868
short review
© Georg Thieme Verlag Stuttgart · New York

Strategies for the Synthesis of N-Arylammonium Salts

Shlomy Arava
Schulich Faculty of Chemistry, Technion – Israel Institute of Technology, Technion City, Haifa, 3200008, Israel   Email: charles@technion.ac.il
,
Schulich Faculty of Chemistry, Technion – Israel Institute of Technology, Technion City, Haifa, 3200008, Israel   Email: charles@technion.ac.il
› Author Affiliations
The authors thank Israel’s Ministry of National Infrastructure, Energy and Water Resources (grant number 216-11-048) for funding.
Further Information

Publication History

Received: 09 April 2017

Accepted after revision: 11 May 2017

Publication Date:
26 June 2017 (online)


Abstract

The N-arylation of tertiary amines to provide sp3 quaternary ammonium salts is a challenge in organic chemistry. To date, no general method for such arylations has been established. Here, we summarize a variety of strategies that have been tested, starting with harsh nucleophilic aromatic substitutions, through to the use of copper catalysis and the application of strong electrophiles, such as phenyl cations and benzynes. The achievements and limitations of each method are summarized, and the challenges yet to be met in the synthesis of charged ammonium compounds are described.

1 Introduction

2 Alkylation of Anilines: The Menshutkin Reaction

3 Arylations

3.1 Nucleophilic Aromatic Substitutions by Tertiary Amines

3.2 Preparation of N-Arylpyridinum Salts from Zincke and Pyrylium Salts

3.3 Arylations Using Phenyl Cations

3.4 Copper-Catalyzed Arylation of N-Heteroarenes

3.5 Benzynes as Aryl Electrophiles

4 Conclusions and Perspective