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The reduction of 2,P-dinitrostyrenes (mainly with alkoxy-or benzyloxy-groups in the 4-and 5-positions) with various reagents is described. Catalytic hydrogenation yields indoles. Hydrazine in the presence of Raney nickel affords the azine and hydrazone of either the nitro-or amino-benzaldehyde from which the nitrostyrene was derived. Lithium aluminium hydride gives a mixture of indoles and cinnolines. Sodium borohydride yields 2, P-dinitrophenylethanes.

Hermidin has been isolated from Mercurialis perennis L. as a colourless, crystalline compound, shown by synthesis to be 5-hydroxy-4-methoxy-1 -methylpyridine-2,6( 1 H,3H)-dione (2), which in aqueous solution exists as a dihydroxy-4-methoxy-1 -methylpyridin-2(1 H) -one (3) or (4). Oxidation of hermidin with nitric acid affords 4-methoxy-1 -methylpyridine-2,3,6-trione (1 6). When equimolecular amounts of the latter and hermidin in aqueous solution are mixed an immediate deep blue solution containing an ion-radical (17) results. Oxidation of hermidin by air in methanolic solution gives 5,5'-di hydroxy-4,4'-dimethoxy-l ,l '-dimethyl-3,3'-bipyridine-2,2',6,6 '-(1 H,1 'H,3Hr3'H) -tetraone (1 8 ) , and in pyridine solution 4,4'-dimethoxy-l,1 '-dimethyl-3,3'-bipyridine-2,2',5,5',6,6'-hexaone (23). Knackmuss' conclusions on the oxidation of 3,6-dihydroxy-4-methylpyridin-2( 1 H) -one (26) have been re-interpreted. 3,4-Dihydroxy-5-methoxy-l -methylpyridin-2( 1 H) -one (7) has been synthesized.

upon Tyne NEI 7RU As a result of methylation, benzoylation, and other chemical experiments, as well as of studies of the conversion into melanin of samples of dopamine specifically labelled with deuterium at each of the a-, p-, 2-, 5-, and 6-positions (separately), a preliminary outline structure is put forward to represent autoxidative dopamine-melanin. This melanin differs considerably from autoxidative dopa-melanin ; in particular, it is suggested that N-C polymeric linkages may be important, and that more uncyclised side chains are present than in dopa-melanin.

upon Tyne NEI 7RU (~)-3,4-Dihydroxyphenyl[~arbo~y-~~C]alanine was converted into melanin, which was oxidised to give pyrrole-2,3,5-tricarboxylic acid, and also decarboxylated. The specific activities of the precursor, the melanin, the acid, the decarboxylated melanin, and the carbon dioxide evolved during the decarboxylation were compared. From the results it was possible to assess approximately the fractions of the polymer units which are ( a ) uncyclised amino-acid units, ( 6 ) carboxylated indole and indoline units, and (c) carboxylated pyrrole units. From the results of methylation experiments the relative proportions of units in the quinonoid and phenolic states were deduced.

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