Treatment of pinto bean and barley seed with 1,4-oxathiin derivatives gave disease control by systemic fungicidal action of such pathogenic fungi as Uromyces phaseoli and Ustilago nuda. The two chemicals, D735 and F461, were highly specific and selective against the pathogens without injury of the hosts.

Konigs first synthesized quinoline in 1879 by passing allylaniline over heated litharge. Shortly after he prepared quinoline by heating the condensation product of aniline and acrolein, thus anticipating the classical Skraup synthesis. This synthesis involves a series of reactions brought about by heating a primary aromatic amine, in which at least one position ortho to the amino group is unsubstituted, with glycerol, sulfuric acid, and an oxidizing agent. The product is a quinoline containing only those substituents that were originally present in the aromatic amine. Quinolines substituted in the hetero ring may be obtained by a modified Skraup synthesis in which a substituted acrolein or a vinyl ketone is used in place of glycerol.

No abstract

7H-Pyrido(2,3-c)-( I X , R = H ) and 7H-pyrido(3,2-c)carbazole (V, R = I-I) have been synthesized by unambiguous routes and shown to be identical with the products resulting from the Fischer-indole ring closure followed by dehydrogenation of 6-and 7-quinolylhydrazo~~e of cyclohexanone respectively. The cyclization of N-substituted-1,2,3,4-tetrahydro-6-and -7-q~~inolylhydrazor~e of cyclohexanone followed by hydrolysis and dehydrogenation resulted in the linear polycyclic systems, GH-pyrido(3,2-b)-(VIII) and 10H-pyrido(2,3-b)carbazole (IV) respectively. The 12 possible pyridocarbazoles have now been prepared.The structure of the Skraup reaction product of 1-phenyl-5-amino-1-benzotriazole ( X ) has been established.The fusion of the carbazole nucleus (I) a t the a , b, and c positions with the pyridine ring (11) a t the 2,3-and 3,4-positions results in 12 isomeric pyridocarbazoles, six belonging to the quinoline and six to the isoquinoline series. The synthesis of the isoquinoline series, namely 11H-pyrido(3,4-a)-, 11H-pyrido(4,3-a)-, 10H-pyrido(3,4-b)-, 6H-pyrid0(4,3-b)-, 7H-pyrido(3,4-6)-, and 7H-pyrido(4,3-c)carbazole, has already been reported (9, 10). Of the pyridocarbazoles belonging to the quinoline series, namely 10H-, and 7H-pyrido(2,3-c)carbazole (IX), three (VI, VII, and IX) have also been recently synthesized (2,3,6) though the structure of IX was not rigorously established. The purpose of this investigation was to conlplete the synthesis of the pyridocarbazoles by unambiguous methods.When 5-, 6-, 7-, and 8-quinolylhydrazone (111) of cyclohexanone undergo a Fischer-indole ring closure the products are tetrahydropyridocarbazoles which on clehydrogenation yield pyridocarbazoles. I t will be noted that only 5-and 8-quinolylhydrazones can produce pyridocarbazoles of undoubted structure, the 6-and 7-quinolylhydrazone each being able to undergo cyclization in two directions. It was therefore necessary to bloclc one of the two positions ortho to the hydrazono group in the latter cases before cyclization and to remove the blocking group afterwards, in eider to accon~plish unequivocal synthesis.For this purpose 5,8-dichloro-6-quinolyll~ydrazone of cyclol~exanone was prepared and subjected to the Fischer indole reaction. Ring closure was accornplished only under the most drastic conditions and the product was 5-chloro-8,9,10,11-tetrahydro-7H-pyrido(2,3-c)carbazole (tetrahydro-IX, R ' = Cl). Apparently the tendency of the 5,s-dichloro-6-quinolyll~ydrazone to ring close to the 5-position was so great that the chlorine in that position was eliminated to form the angular pyridocarbazole. The relative ease with which angular aromatic polycyclic conlpounds form as compared to the linear isomers is a well-known phenomenon (1). The dechlorination of 5-chloro-8,9,10,11-tetrahydro-7H- For personal use only.

Vol. 65 repeated, leaving a viscous tar (D) (25.3 g.). Concentra-tion of the combined petroleum ether solutions (Y', Y", Y'") (water-bath 50-60°), followed by removal of the last traces of solvent under reduced pressure (50°), left a residue of light-colored petroleum ether-soluble ethanolysis oils (43.3 g.) (E).Solvent Group Fractionation of the Petroleum Ethersoluble Ethanolysis Oils.-The petroleum ether-soluble oils (43.3 g.) were dissolved in benzene (300 cc.) and the solution extracted successively with (a) eight 30-cc. portions of aqueous sodium bisulfite (20%), and the bisulfite extract (F) back-extracted with two 30-cc. portions of benzene which were then combined with the main benzene solution; (b) three 30-cc. portions of 8% sodium bicarbonate (back-extraction as in (a)); and (c) eight 35-cc. portions of 5% sodium hydroxide (back-extraction as in (a)). (Each of the sodium hydroxide extracts was neutralized immediately after extraction.) The oil remaining in the benzene solution was the "neutral fraction."Each of the extracted fractions (a), (b) and (c) was then acidified (Congo red) with dilute sulfuric acid. In the case of the bisulfite extract the sulfur dioxide was removed after acidification by use of a carbon dioxide bubbler under reduced pressure. The various acidified solutions were ex-tracted with benzene, the benzene solutions dried with sodium sulfate and the solvent removed under reduced pressure yielding a bisulfite-soluble fraction (10.3 g.); bicarbonate-soluble fraction (0.4 g.); alkali-soluble ("phenol") fraction (24.7 g.) and "neutral" fraction (5.4 g.).