[Formations and reactions of aromatic furazan compounds].
A reaction from various kinds of nitroquinoline with hydroxylamine in potassium hydroxide alkalinity produced a novel product, furazanoquinoline, besides the known amino derivatives. The products obtained were furazano [3,4-f] quinoline (5) from 5-nitroquinoline (1) and 6-nitroquinoline (6), and furazano [3,4-h] quinoline (10) from 7-nitroquinoline (8) and 8-nitroquinoline (11). The reaction mechanism was believed to be as shown in Figs. 2 and 3. The photoreaction of benzofuroxan (19) in acetonitrile containing a little water, under a high pressure mercury lamp, produced 1H-azepine-2,7-dione (20), while under irradiation using a low pressure lamp, 6H-furazano [4,5-c] carbazole-3-oxide (21) and compound 20 were obtained. Then the photoproduct 20 produced photodimer 22 by irradiation in acetonitrile: water (9:1, v/v) using a high or low pressure mercury lamp, while photolysis with alkali proceeded as in the photoreaction of N-alkylimide to give 7-hydroxy-1H-azepine-2-one (23). When pyrido [2,3-c] furoxan (24) was irradiated in acetonitrile containing a little water with a low pressure mercury lamp, 3-nitro-2-pyridone (25) was obtained. When compound 24 was irradiated in the presence of morpholine with a low pressure mercury lamp in an argon atmosphere, 6-morpholinopyridine 2,3-dioxime (26) was produced. Quinoxaline 1,4-dioxide derivatives (31, 33), phenazine 5,10-dioxide derivatives (36, 37) and pyrido [2,3-b] pyrazine derivatives (38, 39) were synthesized from the corresponding furoxan catalyzed by silica gel or molecular sieves, and their antibacterial properties were evaluated. The results of antibacterial screening tests in vitro, revealed strong activity against Bacteroides fragilis.
First synthesis of 2-phosphonylated quinoxaline 1,4-dioxides: an extension to the Beirut reaction
An extension of the Beirut reaction for the preparation of the first members of the 2-phosphonylated quinoxaline 1,4-dioxide series is described. Contrary to their carboxylated equivalents, preparation of these new compounds could not be achieved under basic conditions but required the use of powdered molecular sieves. Good and reproducible yields were obtained only when the initial suspension in THF was transformed into a pasty film by slow evaporation of ca. 90% of the initial solvent volume.
Inhibitors of monoamine oxidase. Influence of methyl substitution on the inhibitory activity of beta-carbolines.
A number of tetrahydro and aromatic β -carbolines, mostly with a methyl substituent at various positions, were synthesized and their in vitro inhibitory activities on monoamine oxidase evaluated. Substitution of a methyl group at the N-9 nitrogen of tetrahydro- β -carboline gave a potent competitive inhibitor of the enzyme. Methyl groups at C-1 of both tetrahydro and aromatic β -carbolines generally reduced the potency, whereas introduction of a methyl group at the N-2 nitrogen of tetrahydro- β -carboline gave a compound of equal activity.