123331-32-8Relevant articles and documents
Regiospecific Synthesis, Structure, and Fluorescence Properties of Highly Substituted Imidazopyridines and Pyridobenzimidazoles
Knoelker, Hans-Joachim,Boese, Roland,Hitzemann, Rainer
, p. 327 - 339 (2007/10/02)
1-(Arylacetyl)imidazoles 1 react with acetylenedicarboxylic esters to provide highly functionalized imidazopyridines 2 in up to 89percent yield.The scope and limitations of this novel condensation reaction have been investigated, and a mechanistic interpretation is presented.A strong effect on the yield of this reaction is observed for electron-donating and electron-withdrawing substituents in the para position of the aryl ring.Moreover, the transformation is shown to proceed in a regiospecific manner starting with 4,5-unsymmetrically substituted 1-(arylacetyl)imidazoles (1d-g) and is extended to the synthesis of the corresponding pyridobenzimazoles 12.The crystal structure of derivative 2a has been determined by X-ray analysis.Imidazopyridines 2 and pyridobenzimidazoles 12, obtained by this procedure, are highly fluorescent in the visible region with characteristically large Stokes shifts.