Garazi Urgoitia

Palladium NCN and CNC pincer complexes as exceptionally active catalysts for aerobic oxidation in sustainable media

The oxidation of secondary benzyl alcohols is catalyzed by two palladacycles at atmospheric pressure in PEG-400, a sustainable reaction media. Recycling of the active catalytic species is performed up to the 5th run, and catalyst loadings decreased down to 10−8 mol%, thus achieving unprecedented TON and TOF values. In addition, the same conditions proved to be effective for the aerobic oxidation of benzyl methylene compounds, a scarcely explored process by palladium catalysts.

Aerobic oxidation at benzylic positions catalyzed by a simple Pd(OAc)2/bis-triazole system

An efficient catalyst system for the Pd-catalyzed aerobic oxidation of benzylic positions has been developed. The combination of palladium(II) acetate and 3,5-bis((1H-1,2,4-triazol-1-yl)methyl)benzoate ligand allows the selective oxidation at carbon adjacent to arene rings (primary and secondary benzylic alcohols, and other benzyl compounds) to provide the corresponding carbonyl and carboxy derivatives, employing molecular oxygen as oxidizing agent and a very low metal loading (10−5 mol%).

Enaminoketone derivatives as key intermediates for the synthesis of 4-quinolones

N-substituted 4-quinolones can be obtained in good yields via intramolecular amine exchage reaction from N-substituted (E)-1-(2-aminophenyl)-3-(dimethylamino)prop-2-en-1-ones or, alternatively, from (E)-1-(2-aminophenyl)-3-(dimethylamino)prop-2-en-1-one through intramolecular amine exchange/N-benzylation. Both strategies can lead to N-(2-halobenzyl)-4-quinolones, functionalized substrates which could undergo further transformations to provide interesting polyheterocycles.

New catalytic systems for oxygen-mediated oxidative processes

The oxidation of alcohols to the corresponding carbonyl compounds is a current transformation in laboratory and industrial chemistry. Traditionally this reaction involves oxidants used in stoichiometric or overstoichiometric amounts so that relatively large quantities of waste are generated. Molecular oxygen is the ideal oxidant (readily available, safe, environmentally friendly, water as waste, etc.), but the need of metal catalysts to control the reaction outcome in relatively high amounts can become a serious drawback.[1],[2] We wish to present two pallacyclic systems with remarkable catalytic properties in the aerobic oxidation of a number of alcohols. [1] Sheldon, R.A.; Arends, I.W.C.E.; ten Brink, G.J.; Dijksman, A. Acc. Chem. Res. 2002, 35, 774-778. [2] Verho, O., Dilenstam, M.D.V.; Karkas, M.D., Johnston, E.V.; Akermark, T.; Backvall, J.E.; Akermark, B. Chem. Eur. J. 2012, 18, 16947-16954.