Carbon-carbon cross-coupling reactions with aryl-Ag(III) and aryl-Cu(III) species

Abstract

In this project we describe a direct comparison between the different reactivity of well-defined aryl-Ag(III) and aryl-Cu(III) compounds. Special attention has been devoted to the carbon-carbon cross-coupling reactions, which are currently of great interest in organic chemistry. These transformations have been studied with two different types of substrates, arylboronic acids and arylsilanes. As already known, the chemistry of palladium highlights are related to the variety of the important products obtained and the versatility in the reaction conditions. The mechanism that is generally proposed is a Pd(0)/Pd(II) two-electron redox catalytic cycle. Other transition metals have appeared more recently as an alternative to palladium, which are much more abundant and less toxic, and might become a substitute for palladium. This refers to copper, which might follow a two-electron redox catalytic cycle similar to palladium. Silver has been recently capable to perform this type of transformations following a Ag(I)/Ag(III) redox cycle. Aryl-Ag(III) and aryl-Cu(III) species have been identified unequivocally as intermediate catalytic cycle and direct evidence of aryl halide oxidative addition and carbon-carbon or carbon-oxygen bond-forming reductive elimination steps has been provided. The different reaction conditions under each of these two complexes react has become a good opportunity to investigate different selectivities that have both and, therefore, it has led to the development of synthetic strategies in an orthogonal way.

Herein, various macrocylic ligands had been used to synthesize the corresponding aryl-Ag(III) and aryl-Cu(III) compounds. A study of the different transformations with arylboronic acids and arylsilanes has been undertaken, obtaining a number of products which were characterized by Nuclear Magnetic Resonance (NMR) and Electrospray Ionization in a high-resolution mass spectrometer (Q-TOF)