Low-valent ruthenium complexes with a π-acidic ligand, such as Ru (η6-cot)(dmfm) 2 [cot= 1, 3, 5-cyclooctatriene, dmfm= dimethyl fumarate] and Ru3 (CO) 12, showed high catalytic activity for the intramolecular hydroamination of aminoalkynes. The reaction is highly regioselective, in which a nitrogen atom is selectively attached to an internal carbon of alkynes to give five-, six-, and seven-membered nitrogen heterocycles as well as indoles ...
