Copper/iron co-catalyzed alkoxycarbonylation of unactivated alkyl bromides

Yahui Li,Xiao-Feng Wu

doi:10.1038/s42004-018-0039-6

Yahui Li, Xiao-Feng Wu

Open Access

https://doi.org/10.1038/s42004-018-0039-6

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Abstract

Carbonylative transformations of alkyl bromides have been explored less than those of aryl halides, in part because of the high barrier to activation of aryl bromides. Additionally, alkyl-metal reagents formed in situ can tend to undergo β-hydride elimination. Here we describe a copper/iron co-catalyzed alkoxycarbonylation of unactivated alkyl bromides. In the presence of catalytic quantities of iron and copper catalysts, primary, secondary, and tertiary alkyl bromides are carbonylatively transformed into the corresponding aliphatic esters in good yields. A potential reaction mechanism is proposed based on control experiments.

Highlights

Carbonylative transformations of alkyl bromides have been explored less than those of aryl halides, in part because of the high barrier to activation of aryl bromides
Numerous cross-coupling reactions of alkyl halides have been reported[6,7,8], but by contrast, their carbonylative transformations often encounter increased difficulties. This situation can mainly be explained by the following three reasons: (i) further increased difficulty in the oxidative addition step due to the presence of πacidic carbon monoxide (CO), which decreases the electron density on the metal center; (ii) fast subsequent β-hydride elimination, and the produced metal-hydride will react with substrates and catalysis; (iii) facile nucleophilic substitution reaction between alkyl halides and nucleophiles
We describe the copper/iron co-catalyzed carbonylative transformation of primary, secondary, and tertiary alkyl bromides into the corresponding esters using alcohols as the reaction partner (Fig. 1c)

Summary

Introduction

Carbonylative transformations of alkyl bromides have been explored less than those of aryl halides, in part because of the high barrier to activation of aryl bromides. We describe the copper/iron co-catalyzed carbonylative transformation of primary, secondary, and tertiary alkyl bromides into the corresponding esters using alcohols as the reaction partner (Fig. 1c). CuTc or CuBr(Me2S) (X mol%) L8 (X mol%), Fe3(CO)[12] (X mol%), NaOMe, Y bar CO Toluene/MeOH (4:1), 80 °C, 48 h

Results

Conclusion