Recent advances in the synthesis of indoles via C–H activation aided by N–N and N–S cleavage in the directing group

Abstract

Transition metal‐catalysed C–H activation strategies with the use of diverse directing groups have emerged as regioselective, chemoselective, and step economic tools for the synthesis of the biologically relevant indole nucleus. This review highlights the synthesis of indoles using C–H activation assisted by directing groups containing N–N and N–S bonds. An N‐atom within the directing group transforms into the indolyl nitrogen while the cleaving N–N/N–S bonds within the directing group act as internal oxidants for the completion of the catalytic turnover.

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

“…An approach is to employ O 2 or air as clean oxidant [5e,8] . Another approach is to employ the substrates which contain an internal oxidant such as N−N bonds and N−S bonds [4b,9] . Electric current can be used to promote ruthenium‐catalyzed C−H activation/annulation processes to realize the synthesis of indoles from alkynes and aniline derivatives [10] .…”