Ruthenium catalyzed directing group-free C2-selective carbenoid functionalization of indoles by alpha-aryldiazoesters.

A directing group-free approach for C2-selective carbenoid functionalization of NH-indoles is presented. Using [RuCl(2)(p-cymene)](2) as catalyst and alpha-aryldiazoesters as carbenoid source, 2-alkylated indoles were obtained in up to 96% isolated yield. Similarly, a regioselective carbenoid functionalization of NH-pyrroles was also achieved.