Enamine-Functionalized Oligopyridines as Convenient Intermediates for the Synthesis of Carbaldehyde Derivatives

Abstract

A series of enamine-substituted bipyridine, biquinoline and o-phenanthroline chromophores has been synthesized and fully characterized. The para regioselectivity of the functionalization is discussed on the basis of 2D NOESY correlation and X-ray diffraction analysis. Absorption and emission spectroscopic studies allow a comparison of the acceptor strength of the heterocyclic core (biquinoline > phenanthroline > bipyridine). These enamine derivatives are key intermediates for a straightforward preparation of the corresponding dicarbaldehyde-bisimine compounds.

Key words

heterocycles - imines - ligands - aldehydes - chromophores

References

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Other sources of NaIO₄ gave only poor yield.