Alternate pathway for the click reaction of 2-(2-azidophenyl)-4,5-diaryloxazoles.

Pravin C Patil, Frederick A Luzzio
Author Information
  1. Pravin C Patil: Department of Chemistry, University of Louisville, 2320 South Brook Street, Louisville, Kentucky 40292 USA.
  2. Frederick A Luzzio: Department of Chemistry, University of Louisville, 2320 South Brook Street, Louisville, Kentucky 40292 USA.

Abstract

The CuSO/ascorbate-mediated 'click' reaction of 2-(2-azidophenyl)-4,5-diaryloxazoles and arylacetylenes proceeded through an alternate pathway whereby reduction of the azide predominated over formation of the 1,2,3-triazole-forming cycloaddition. The unimolecular product, 2-(2-aminophenyl)-4,5-diphenyloxazole, was isolated which appears to be a formal reduction of the arylazide to the corresponding arylamine. A series of oxazoles which possessed various substituents (F, Cl, Br, OCH) on the 4,5-diaryl rings and having the 2-azido group on the 2-oxazolylphenyl position were submitted to the same 'click' conditions and gave the corresponding arylamine products (73-99%). The reaction appears to be specific toward the -azido substitution of the polycyclic system, as the corresponding azidomethyl-substituted phenyl oxazoles do not give the 'reduction' products but gave the expected click products with the acetylenic co-reactants.

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Grants

  1. R01 DE023206/NIDCR NIH HHS

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