The adverse effect of an electron-releasing group in this reaction is probably due to its activation of the ring towards a Friedel-Crafts type of substitution by the acyl moiety in the presence of polyphosphoric acid. This was partly borne out by the presence of a carbonyl band in the infrared spectrum of the tarry reaction products. On the other hand, p-azidobenzoic acid (I; R1 = C02H, R2 = H) and 4-nitronaphthyl azide furnished the expected oxazoles. Similarly, 3-azido- quinoline and ...
