Ioannis D. Kostas - Research

TRANSITION-METAL HOMOGENEOUS CATALYSIS

In the recent year, our research activities are focused to TRANSITION-METAL HOMOGENEOUS CATALYSIS and applications to organic synthesis.
Transition-metal homogeneous catalysis, which was established from the discovery of hydroformylation (1938, Otto Roelen/Ruhrchemie), today is undoubtedly a highly competitive research field with enormous academic and industrial interest. The development of homogeneous catalysis at the Institute of Organic and Pharmaceutical Chemistry of the National Hellenic Research Foundation started at the end of the 20th century (by I.D. Kostas). Today, our investigations include the development of transition-metal complexes with novel ligands and their evaluation as catalysts in reactions such as:

• Hydroformylation. It has been recognized as the largest volume industrial application of homogeneous catalysis employing organometallic catalysts and represents the best technology for the synthesis of aldehydes from olefins.
• Hydroaminomethylation. It is a domino hydroformylation-reductive amination reaction, which leads to secondary and tertiary amines.
• Hydrogenation. It is one of the most well-established homogeneously catalyzed processes.
• Coupling reactions. Heck and Suzuki reactions, for instances, are among the most versatile tools of organic chemistry for C-C bond forming reactions.

More specifically, the research activities include:

• Catalysis by hybrid and hemilabile phosphorus ligands
• Catalysis in air by phosphine-free ligands
• Catalysis by dinuclear aryloxide- and carboxylate-bridged complexes
• Asymmetric catalysis
• Catalysis by high energy techniques
• Catalysis by dendrimers
• Aqueous catalysis

Catalysis by hybrid and hemilabile phosphorus ligands
The project includes the development of transition metal (e.g. Rh, Pd) complexes with functionalized hybrid and hemilabile phosphorus ligands (e.g. phosphines, phosphine oxides, phosphinites, mixed phosphine-phosphinites) possessing additional potent donors such as oxygen, nitrogen, sulfur, and their applications to homogeneous catalysis (hydroformylation, hydroaminomethylation, hydrogenation, Heck reaction). Part of this research is being with collaboration with the Favorsky Irkutsk Institute of Chemistry, Siberian Branch of Russian Academy of Sciences (Russia) (Prof. S. Amosova) and the University of Athens (Prof. P. Kyritsis).

Selected complexes

Recent selected publications

• I.D. Kostas J. Organomet. Chem. 2001, 626, 221
• I.D. Kostas J. Organomet. Chem. 2001, 634, 90
• I.D. Kostas Inorg. Chim. Acta 2003, 355, 424
• I.D. Kostas, B.R. Steele, A. Terzis, S. V. Amosova Tetrahedron 2003, 59, 3467
• I.D. Kostas, B.R. Steele, F.J. Andreadaki, V.A. Potapov Inorg. Chim. Acta 2004, 357, 2850
• E.I. Tolis, K.A. Vallianatou, F.J. Andreadaki, I.D. Kostas Appl. Organomet. Chem. 2006, 20, 335
• K.A. Chatziapostolou, K.A. Vallianatou, A. Grigoropoulos, C.P. Raptopoulou, A. Terzis, I.D. Kostas, P. Kyritsis, G. Pneumatikakis J. Organomet. Chem. 2007, 692, 4129

Catalysis in air by phosphine-free ligands
Palladium-catalysed cross-coupling reactions are amongst the most powerful tools in organic synthesis for carbon-carbon bond formation. The complexes used as catalysts are usually based on phosphorus ligands, which are often water- and air-sensitive. Therefore, catalysis under phosphine-free conditions is a challenge of high importance. In our attempts to evaluate phosphine-free systems in cross-coupling reactions, substituted salicylaldehyde thiosemicarbazones were chosen for this purpose. This project in collaboration with Prof. D. Kovala-Demertzi (University of Ioannina) includes the development of novel palladium complexes with thiosemicarbazones and their applications to cross-coupling reactions. Recently, for the first time, we used thiosemicarbazones as catalyst precursors for palladium-catalyzed coupling reactions (Heck, Suzuki), under aerobic conditions.

Selected complex

Recent publications

• I.D. Kostas, F.J. Andreadaki, D. Kovala-Demertzi, C. Prentjas, M.A. Demertzis Tetrahedron Lett. 2005, 46, 1967
• D. Kovala-Demertzi, P.N. Yadav, M.A. Demertzis, J.P. Jasinski, F.J. Andreadaki, I.D. Kostas Tetrahedron Lett. 2004, 45, 2923.

Additionally, in collaboration with Favorsky Irkutsk Institute of Chemistry, we developed a synthetic route to S-, Se-, Te-containing Schiff bases, the palladium complexes of which were successfully applied to the Suzuki coupling, in air.

Selected complex

Recent selected publication

• I.D. Kostas, B.R. Steele, A. Terzis, S.V. Amosova, A.V. Martynov, N.A. Makhaeva Eur. J. Inorg. Chem. 2006, 2642

Catalysis by dinuclear aryloxide- and carboxylate-bridged complexes
The project in collaboration with Prof. J. Vohlidal (Charles University, Prague) and Prof. P. Kyritsis (University of Athens) deals with the ultrasound-assisted synthesis of dinuclear aryloxide- and carboxylate-bridged rhodium complexes and their evaluation in the hydroformylation reaction.

Selected complexes

Recent publication

• I.D. Kostas, K.A. Vallianatou, P. Kyritsis, J. Zednik, J. Vohlidal Inorg. Chim. Acta 2004, 357, 3084

Asymmetric catalysis
This project in collaboration with Prof. A. Borner (Leibniz-Institut fur Katalyse an der Universitat Rostock) includes the development of rhodium complexes with new chiral amino diphosphite, phosphonite, phosphine-phosphoramidite and phosphite-phoephoramidite ligands and their applications to enantioselective hydroformylation and hydrogenation. Recently, we developed the chiral ligand Me-AnilaPhos as a highly efficient ligand for the rhodium-catalyzed enantioselective olefin hydrogenation.

Selected complexes and ligands

Recent selected publications

• I.D. Kostas, K.A. Vallianatou, J. Holz, A. Börner Appl. Organomet. Chem. 2005, 19, 1090
• K.A. Vallianatou, I.D. Kostas, J. Holz, A. Börner Tetrahedron Lett. 2006, 47, 7947
• I.D. Kostas, K.A. Vallianatou, J. Holz, A. Börner Tetrahedron Lett. 2008, 49, 331

Catalysis by high energy techniques
The project includes the application of a microwave irradiation to homogeneous catalysis. Recently, we used this technique to the Suzuki coupling in air, catalyzed by a palladium complex with a thiosemicarbazone ligand. Although the complex was inactive as catalyst for the Suzuki coupling under a conventional heating, a microwave irradiation promoted the effective catalytic activity of the complex, under strictly similar conditions with those used under conventional heating. The microwave-promoted cross-coupling reaction by palladium complexes with thiosemicarbazones provides a convenient approach compared to existing methods that require an inert atmosphere due to the air-sensitive nature of other catalysts.

Recent publication

• I.D. Kostas, G.A. Heropoulos, D. Kovala-Demertzi, P.N. Yadav, J.P. Jasinski, M.A. Demertzis, F.J. Andreadaki, G. Vo-Thanh, A. Petit, A. Loupy Tetrahedron Lett. 2006, 47, 4403

Catalysis by dendrimers
The project in collaboration with Prof. G.S. Hanan (Universite de Montreal) deals with the development of functionalized triazine and terpyridine dendrimers, and their applications to transition-metal catalysis.

Aqueous catalysis
The replacement of organic solvents by water in transition metal homogeneous catalysis has received remarkable attention, as water is inexpensive, non-toxic, non-flammable, environmentally sustainable, and allows simple separation and reuse of the catalyst. The present project in collaboration with Prof. A. Coutsolelos (University of Crete) includes the development of water soluble porphyrins and their use as ligands in metal-catalyzed reactions in aqueous media. Recently, we published the first study concerning the evaluation of a porphyrin ligand as a precatalyst in cross-coupling reactions. A palladium complex with a phosphine-free and water-soluble potassium carboxylate salt of a porphyrin, was successfully applied in the Suzuki-Miyaura reaction of phenylboronic acid with aryl bromides, in neat water, under aerobic conditions. The catalyst could be easily recycled and reused.

Recent publication
I.D. Kostas, A.G. Coutsolelos, G. Charalambidis, A. Skondra Tetrahedron Lett. 2007, 48, 6688