Ruthenium(II)- or Rhodium(III)-Catalyzed Grignard-Type Addition of Indolines and Indoles to Activated Carbonyl Compounds

The ruthenium(II)- or rhodium(III)-catalyzed pyrimidinyl-directed Grignard-type C-H additions of N-heterocycles with activated aldehydes and ketones are described. A cationic ruthenium catalyst and sodium acetate additive in dichloroethane as solvent were found to be optimal catalytic system for the construction of C-7 alkylated indolines. In sharp contrast, a cationic rhodium complex allows the generation of C-2 alkylated indoles and pyrroles as well as C-1 alkylated carbazoles. The site-selective C-H functionalization of these heterocyclic scaffolds could be an important asset towards the development of novel bioactive compounds.