Reductive hydrolytic fission of violacein gives, in high yield, a colourless acid, CzoHlaOaNz, which on the basis of chemical and spectroscopic evidence is formulated as a y-(5-hydroxy-3-indolyl)-a-oxindolyl-y-oxobutyric acid (VII). IN earlier papers of this series it has been argued that violacein, the pigment of Chromobacterium violaceurn, contains a 5-hydroxyindole nucleus, an oxindole nucleus, and probably a hydroxypyrrole residue. The present communication is concerned with the structure of a colourless acidic degradation product, C,,H,,O,N,, obtained from violacein by the action of alkali in the presence of zinc. If, as now seems likely, the molecular formula of violacein proves to be of the type C2~-N, (see Part I11 *), then only one carbon atom and one nitrogen atom are lost in the formation of this C,,-acid, a conclusion which is consistent with the high yield of the acid and with the simultaneous production of ammonia, identified as toluene-9-sulphonamide, during the degradation.The behaviour of the C,,-acid with methylating agents showed that it is a phenolic acid containing two other weakly acidic replaceable hydrogen atoms. Thus with diazomethane the acid gave a phenolic methyl ester (a monomethyl derivative) which, rather surprisingly, was also formed by the action of methyl iodide and potassium carbonate in boiling acetone. With methyl sulphate and an excess of alkali the C,,-acid gave an acidic trimethyl derivative containing one methoxyl group, whilst the use of an excess of methyl sulphate, so that the reaction mixture finally became acidic, yielded a neutral tetramethyl derivative with two methoxyl groups. The latter compound is clearly the methyl ester of the trimethyl derivative, from which it was prepared by methyl iodide-potassium carbonate. The position of the methyl groups in the trimethyl derivative is established by the oxidation with potassium permanganate to l-methylisatin (I; R = H) and 5-methoxy-l-*
