Sequential one pot double C-H heteroarylation of thiophene using bromopyridines to synthesize unsymmetrical 2,5-bipyridylthiophenes

We present C-H heteroarylation reactions between thiophene and variously substituted bromopyridines. The objective was to synthesize unsymmetrical 2,5-bipyridylthiophenes. We studied the reaction conditions allowing to a sequential one-pot double C-H heteroarylation, in a view to introduce two different pyridyl moieties at positions 2 and 5 of the thiophene ring using bromopyridines. 11 original unsymmetrical 2,5-bipyridylthiophenes were synthesized and characterized, including 2,5-di(pyridin-2yl)thiophenes for which the preparation by classical cross-coupling reactions is challenging. Finally, with the additional synthesis of both an unsymmetrical 2,5-biarylthiophene and an original pyrimidinthiophene-furan scaffold, we shown that our methodology was also an efficient tool to access to new heterocyclic sequences. (C) 2017 Elsevier Ltd. All rights reserved.