Metal‐Free Arylation of Pyridine/Quinoline N‐Oxides with Indoles

Abstract We achieved metal‐free pyridine arylations via O ‐triflated pyridine N ‐oxides and N ‐alkylated indoles. The reactions proceeded through reactive intermediates, obtained upon treatment of pyridine N ‐oxides with Tf 2 O, which were sufficiently activated for preferentially installing various indoles at the nitrogen‐adjacent positions of pyridine. This protocol features mild conditions, short reaction times, and ease of handling under stirring and air at room temperature. Furthermore, no transition metal is required, which renders our procedure an environmentally benign approach to pyridine arylation.