Unsymmetrical Diaryliodonium Salts as Aryne Synthons: Renaissance of a C–H Deprotonative Approach to Arynes

Dedicated to the memory of Prof. J. D. Roberts

Abstract

A regio- and chemoselective C–H deprotonative strategy toward arynes is described that employs a hypervalent iodine leaving group. The unsymmetrical aryl(mesityl)iodonium salts used as aryne precursors are readily synthesized from commercially available aryl iodide and arylboronic acid building blocks. The bases LiHMDS and NaOt-Bu engage the diaryliodonium salts in a deprotonation event at an aromatic C–H bond and the transient arynes react in cycloaddition reactions with furan and benzyl azide or nucleophilic addition reaction with alicyclic amines. The auxiliary component of aryl(auxiliary)iodonium salts can be sterically tuned to influence the regioselectivity of the C–H deprotonation event for meta-substituted aryl groups.

1 Introduction

2 Iodonium Salts as Aryne Precursors

3 Reaction Discovery and Optimization

4 Reaction Scope

5 Auxiliary-Controlled Regioselective Deprotonation

6 Beyond Cycloaddition with Furan

7 Conclusions and Outlook

Key words

aryne - arylation - cycloaddition - heterocycles - iodine - nucleophilic­ addition - regioselectivity - chemoselectivity

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