A reusable enantioselective catalytic system for the Kharasch–Sosnovsky allylic oxidation of alkenes based on a ditopic azabis(oxazoline) ligand

• Published in: Tetrahedron Vol. 68; no. 17; pp. 3417 - 3422
• Main Authors: Aldea, Luis, Delso, Ignacio, Hager, Markus, Glos, Martin, García, José I., Mayoral, José A., Reiser, Oliver
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 29-04-2012
• Subjects: Addition polymerization; Allylic oxidation; Bis(oxazoline) ligands; Catalysis; Catalysts; Coordination polymers; Copper catalysis; Kharasch–Sosnovsky oxidation; Ligands; Reusable; Self assembly; Solvents; Supported catalysts; Supported catalysts; Kharasch–Sosnovsky oxidation; Allylic oxidation; Bis(oxazoline) ligands; Copper catalysis
• ISSN: 0040-4020; 1464-5416
• DOI: 10.1016/j.tet.2011.10.009

An easily recoverable and reusable enantioselective catalytic system based on the self-assembly of a coordination polymer through the use of a chiral ditopic ligand, is described for the allylic oxidation of cycloalkenes with tert-butyl perbenzoate. Upon addition of the substrates and a coordinating solvent (acetone or acetonitrile) the coordination polymer disassembles, allowing the catalysis to take place in homogeneous phase. After completion of the reaction, the catalyst reassembles as a coordination polymer upon solvent evaporation and addition of hexane, and is recovered as an insoluble solid. This way, good enantioselectivities and yields are obtained in seven consecutive operation cycles.
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