Gold-catalyzed C5-alkylation of indolines and sequential oxidative aromatization: access to C5-functionalized indoles.

A novel protocol for the synthesis of C5-alkylated indole derivatives via a gold-catalyzed reaction of indolines with diazo compounds and subsequent oxidative aromatization has been developed. C-H bond functionalization selectively occurs at the C5-position of indolines without a directing group. The experimental operation is simple and the whole process can be manipulated in one-pot.