New Access to Oxazolopyridines via Hydroxyamidine Derivatives; Application to Quinolines

Abstract

Several 2-aryl and 2-heteroaryloxazolo[4,5-b]pyridines were synthesised in high yields from zwitterion or hydroxyamidine derivatives by heating in dimethylacetamide. These intermediates were generated via hetarynic reaction with the complex base NaNH₂-t-BuONa (5:2). The same reactions were possible with quinoline derivatives.

Key words

cyclizations - heterocycles - zwitterions - pyridines - quinolines

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Supplementary X-ray crystallographic data: Cambridge Crystallographic Data Centre, University Chemical Lab, Lensfield Road, Cambridge CB2 1EW, UK; e-mail: http/[e-mail].