reaction mixture with water. Due to its particular structure the diquinolinium ditribromide 4 also proved quite stable in the 5-hydroxy form. None the less, after treatment with acetone (to bind excess bromine) and then water, the typical 4-hydroxyquinolone bromocyclization product 2-bromomethyl-7,8-dimethoxy-5-oxo-1,2-di-hydro-5H-oxazolo[3,2-a]quinoline-4-carboxylic acid isopropylamide 3 was obtained. The 5-methyl-substi-tuted oxazoloquinolinium bromides 9 (R = Me) are unable to undergo a similar transformation and remain unchanged after addition of water