Palladium-catalyzed, unsymmetrical homocoupling of thiophenes via carbon–sulfur bond activation: a new avenue to homocoupling reactions

/CN/SMe arrangement breaks the routine. The cooperative performance of the functional groups in thiophenes would open up a new vision in the field of metal catalysis homocoupling reactions by joining the electrophilic and nucleophilic motifs of the substrate. Furthermore, it is found that the α-chelating effect of the carbonyl group in amino thiophene offers a new class of synthetic protocols for C-N cross-coupling with arylboronic acids. The bidentate N,O-chelation provides a series of advantages such as copper-catalyzed, ligand- and base-free under open-flask conditions. Interestingly, the combination of the C-N cross-coupling/homocoupling reactions in a domino fashion led to the bithiophene adducts featuring the C(Ar)-N bond cleavage in the nitrogen that bridged between the two thiophene units.

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