Aminoketone, oxazole and thiazole synthesis. Part 15.1 2-[4-(4-halobenzenesulphonyl)-phenyl]-5-aryloxazoles

Acylaminoacylation of aromatic hydrocarbons (benzene, toluene, meta-xylene, mesitylene) with 2-[4-benzenesulfonyl-(4-halophenyl)]-5-oxazolones in the presence of anhydrous aluminum chloride leads to 2-aza-1,4-diones 5 which cyclize under the action of phosphorus oxychloride yielding the corresponding 2-[4-(4-halobenzenesulphonyl)-phenyl]-5-aryloxazoles 6. The parahalogens are chloro or bromo atoms. Electronic absorption, vibrational, 1 H-NMR and 13C-NMR spectral data are presented. The UV and NMR spectra provide evidence for the non-coplanarity of the oxazole and mesityl rings.