Improving alkynyl(aryl)iodonium salts: 2-anisyl as a superior aryl group.

David J Hamnett,Wesley J Moran

doi:10.1039/c4ob00556b

Abstract

The majority of alkynyl(aryl)iodonium salts reported in the literature are derived from iodobenzene. This article describes the effects of varying this iodoarene building block on the synthesis, reactivity and stability of these salts. Two procedures to synthesize a variety of known and novel alkynyl(aryl)iodonium tosylates directly from the iodoarene are reported. In the reactions of these salts, those derived from 2-iodoanisole gave superior results than the others tested in every reaction. Isothermal microcalorimetry indicated that these novel salts were significantly more stable and less prone to decomposition than all of the other derivatives.

Highlights

Interest in hypervalent iodine chemistry has surged in recent years with new iodine(III) and iodine(V) compounds being reported regularly alongside novel reactions using these species.[1]
We identified two different reactions from the literature that alkynyl(aryl)iodonium salts undergo and decided to compare and contrast the effect of varying the aryl moiety on the reaction outcomes
For aryl iodides with electron-withdrawing substituents, the hydroxy(tosyloxy)iodine(III) species were first prepared in situ and treated with the alkyne to generate the iodonium salts in high purity after crystallization from the reaction mixture (Table 2)

Summary

Introduction

Interest in hypervalent iodine chemistry has surged in recent years with new iodine(III) and iodine(V) compounds being reported regularly alongside novel reactions using these species.[1]. Scheme 2 Two reactions of alkynyl(aryl)iodonium salts. For aryl iodides with electron-donating substituents, slow addition of the oxidant over several hours to the reaction mixture at 0 °C provided high purity iodonium salts upon crystallization from the reaction mixture (Table 1).

Results

Conclusion