Straightforward Synthesis of 3‐Aminothiophenes Using Activated Amides

Herein, we describe a facile approach towards the synthesis of diversely substituted 3‐aminothiophenes. A wide range of functional groups can be incorporated at the C(2), C(4), and C(5) positions of the thiophenes, and this route is also suitable for the synthesis of fused bicyclic heterocycles such as 3‐aminotetrahydrobenzothiophenes. This methodology relies on a 6π‐electrocyclization involving a vinyl sulfide linked to a keteniminium salt, the latter being formed in‐situ through activation of the corresponding amide with triflic anhydride.