Alternate pathway for the click reaction of 2-(2-azidophenyl)-4, 5-diaryloxazoles. Issue 38 (19th September 2018)

• Record Type: Journal Article
• Authors: Patil, Pravin C.; Luzzio, Frederick A.
• Is Part Of: Tetrahedron letters. Volume 59:Issue 38(2018)
• Page Start: 3458
• Page End: 3460
• Publication Date: 2018-09-19
• Subjects: Amines -- Azides -- Click chemistry -- Nitrenes -- Reduction; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tetlet.2018.07.062
• Languages: English
• ISSNs: 0040-4039

Abstract

Graphical abstract: Highlights: Structurally specific arylazides may be reduced to amines. The reduction is independent of any acetylenic reacting components. The reaction may be an alternative to standard types of azide reductions. The pathway of the Cu-mediated reduction may involve nitrene intermediates. Abstract: The CuSO4 /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, OCH3 ) 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 ortho -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.