Synthesis of 2‐Methylindoles through Ruthenium(II)‐Catalyzed Reaction of Aniline Derivatives with Allylamines.

The ruthenium(II)‐catalyzed reaction of aniline derivatives with allylamines was carried out, affording 2‐methylindoles via C−H/C−N bond activation. 4,5‐Dimethyl pyrimidin‐2‐yl group attached on the nitrogen atom of anilines is the most effective directing group and N‐allyl‐4‐fluoro‐N‐methylaniline is the optimal allylamine. The cyclization products were obtained in 16% to 96% yields. The method does not require external oxidant. A possible mechanism is proposed. [ABSTRACT FROM AUTHOR]