4-Methyl-6-hydroxycarbostyril is oxidized in good yield with chromic acid or lead tetraacetate to 4-methylcarbostyr il-5, 6-quinone. Dry hydrogen chloride adds to this substance with formation of 4-methyl-5, 6-dihydroxy-8-chlorocarbo-styril. The latter forms a diacetyl derivative with acetic anhydride but a tribenzoyl derivative with benzoyl chloride in pyridine. Oxidation of 4-methyl-5, 6-dihydroxy-8-chlorocarbostyril with chromic acid leads to 4- ...
