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Updated: Jan 5, 2026
The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes
Published on: April 10, 2015
Indoles from Alkynes and Aryl Azides: Scope and Theoretical Assessment of Ruthenium Porphyrin-Catalyzed Reactions
Daniela Intrieri1, Daniela Maria Carminati2, Paolo Zardi3
1Department of Chemistry, University of Milan, Via Golgi 19, 20133, Milan, Italy.
Abstract:
A symbiotic experimental/computational study analyzed the Ru(TPP)(NAr)2 -catalyzed one-pot formation of indoles from alkynes and aryl azides. Thirty different C3 -substituted indoles were synthesized and the best performance, in term of yields and regioselectivities, was observed when reacting ArC≡CH alkynes with 3,5-(EWG)2 C6 H3 N3 azides, whereas the reaction was less efficient when using electron-rich aryl azides. A DFT analysis describes the reaction mechanism in terms of the energy costs and orbital/electronic evolutions; the limited reactivity of electron-rich azides was also justified. In summary, PhC≡CH alkyne interacts with one NAr imido ligand of Ru(TPP)(NAr)2 to give a residually dangling C(Ph) group, which, by coupling with a C(H) unit of the N-aryl substituent, forms a 5+6 bicyclic molecule. In the process, two subsequent spin changes allow inverting the conformation of the sp2 C(Ph) atom and its consequent electrophilic-like attack to the aromatic ring. The bicycle isomerizes to indole via a two-step outer sphere H-migration. Eventually, a 'Ru(TPP)(NAr)' mono-imido active catalyst is reformed after each azide/alkyne reaction.
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