Asymmetric Catalysis; 140: [1] Tris(2-pyridyl)methane Derivatives with a Chiral Bridging Atom

Abstract

Two different series of C ₁-symmetric tris(2-pyridyl)methane tripod ligands were synthesized with pyridin-2-yl, 6-phenylpyridin-2-yl and 6-methoxy- or 6-menthyloxypyridin-2-yl substitutents. The menthoxy devivatives were resolved with respect to the bridging carbon atom by chromatography. In reactions with CuCl₂ and RhCl₃ complexes were obtained which could be analyzed by X-ray crystallography. In the formation of the Rh complex an ortho-metallation of the 6-phenyl substituent occurred giving rise to a Δ/Λ-element of chirality. Whereas the chiral tripod ligand conferred a stable configuration to the Rh atom, a fast equilibration of the Δ- and Λ-isomers was observed.

Key words

chiral tripod ligands - tris(2-pyridyl)methane derivatives - Cu-complex - Rh-complex - ortho-metallation - absolute configuration

1

X-ray structure analyses.

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1

X-ray structure analyses.

2

Brunner, H.; Maier, R. J.; Zabel, M. Z. Naturforsch., 2001, Part 139 in press.