Pd-catalyzed decarboxylative Heck vinylation of 2-nitrobenzoates in the presence of CuF2

Lukas J Gooßen,Thomas Knauber,Bettina Zimmermann

doi:10.3762/bjoc.6.43

Abstract

A new protocol for the decarboxylative Heck vinylation of benzoic acids is disclosed. In the presence of a catalyst system generated in situ from Pd(OAc)2 (2 mol %), CuF2 (2 equiv), and benzoquinone (0.5 equiv) in NMP, a wide range of olefins were coupled with various 2-nitrobenzoates at 130 °C with the release of carbon dioxide to afford the corresponding vinyl arenes in good yields.

Highlights

The palladium-catalyzed coupling of olefins with aryl or vinyl substrates, developed by Mizoroki [1] and Heck [2,3] in the 1970s, is one of the most important, reliable and generally applicable reactions for carbon–carbon bond formation in organic synthesis
In our search for a silver-free catalyst system for decarboxylative Heck reactions, we chose the conversion of 2-nitrobenzoic acid (1a) with styrene (2a) to yield 2-nitro-stilbene (3aa) as a model reaction, and investigated the catalytic activity of various combinations of palladium precursors, additives and oxidants (Table 1)
We were able to show that decarboxylative Heck reactions can be performed with carboxylic acids that cannot be decarboxylated at a palladium catalyst

Summary

Introduction

The palladium-catalyzed coupling of olefins with aryl or vinyl substrates, developed by Mizoroki [1] and Heck [2,3] in the 1970s, is one of the most important, reliable and generally applicable reactions for carbon–carbon bond formation in organic synthesis. This decarboxylative Heck reaction allows the direct conversion of benzoic acids without prior activation, but requires the addition of stoichiometric amounts of both base and an oxidant.

Results

Conclusion