Copper(I) Thiophene-2-carboxylate (CuTC)

Introduction

In the early 1990s, the influence of co-catalytic copper(I) salts on Stille cross-coupling reactions was reported. The copper effect soon found application in numerous other palladium-catalyzed C-C bond forming reactions. [1] As it was suggested, that the cross coupling protocol could be mediated by simple copper salts alone, [1] various copper(I) carboxylates were screened and it was shown that ­copper(I) thiophene-2-carboxylate (CuTC) mediates most efficiently intermolecular cross-coupling reactions of ­aryl, heteroaryl and vinylstannanes with vinyl iodides at low temperature in high yields. [2]

Soon, CuTC found application not only in a number of different types of cross-coupling reactions [4] [6-8] but also in enantioselective allylation reactions [10] and very recently in asymmetric 1,4-additions. [11] [12] CuTC can be easily prepared in multigram scale from thiophene-2-carboxylic acid and Cu₂O upon heating in toluene and azeotropic ­removal of water (Scheme 1). The obtained product is a tan, air-stable powder, which can be stored and handled at room temperature without any special precautions. [2]

Scheme 1 Preparation of CuTC

References

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