The behavior of dimethylamino-substituted 2,5-diaryloxazoles and 2,5-diaryl-1,3,4-oxadiazoles under Vilsmeier-Haack conditions

It has been shown that dimethylamino-substituted 2,5-diaryloxazoles and 2,5-diaryl-1,3,4-oxadiazoles undergo heterocyclization under Vilsmeier-Haack conditions with the participation of the dimethylamino group to form quinazolinium salts. The oxazole ring can also be formylated at the free 4 position. In alkaline medium the quinazolinium ring is readily hydrolyzed with desalkylation.