Faculté des sciences

New synthetic routes toward enantiopure nitrogen donor ligands

Sala, Xavier ; Rodríguez, Anna M. ; Rodríguez, Montserrat ; Romero, Isabel ; Parella, Teodor ; Zelewsky, Alexander von ; Llobet, Antoni ; Benet-Buchholz, Jordi

In: The Journal of Organic Chemistry, 2006, vol. 71, no. 25, p. 9283 -9290

New polypyridylic chiral ligands, having either C₃ or lower symmetry, have been prepared via a de novo construction of the pyridine nucleus by means of Kröhnke methodology in the key step. The chiral moieties of these ligands originate from the monoterpen chiral pool, namely (-)-α-pinene ((-)-14, (-)-15) and (-)-myrtenal ((-)-9, (-)-10). Extension of the... Plus

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    Summary
    New polypyridylic chiral ligands, having either C₃ or lower symmetry, have been prepared via a de novo construction of the pyridine nucleus by means of Kröhnke methodology in the key step. The chiral moieties of these ligands originate from the monoterpen chiral pool, namely (-)-α-pinene ((-)-14, (-)-15) and (-)-myrtenal ((-)-9, (-)-10). Extension of the above-mentioned asymmetric synthesis procedure to the preparation of enantiopure derivatives of some commonly used polypyridylic ligands has been achieved through a new aldehyde building block ((-)-16). As an example, the synthesis of a chiral derivative of N,N-bis(2-pyridylmethyl)ethylamine (bpea) ligand, (-)-19, has been performed to illustrate the viability of the method. The coordinative ability of the ligands has been tested through the synthesis and characterization of complexes [Mn((-)-19)Br₂], (-)-20, and [RuCl((-)-10)(bpy)](BF₄), (-)-21. Some preliminary results related to the enantioselective catalytic epoxidation of styrene with the ruthenium complex are also presented.