9-Aryl-3-methyl-1 : 2 : 10-triazaphenanthrenes (11) have been prepared byThe derived mono-cyclisation of arylamidopyridazines (I ; R = NHCOAr) .methiodides were biologically inactive.PREVIOUS papers have described the synthesis of triazaphenanthrenes from quinolines and cinnolines. Work based on pyridazine derivatives (I) js now described.The pyridazine (I; R = OH) was prepared by dehydrogenation of the pyridazinone obtained from hydrazine and a-phenyl-kvulic acid (cf. ref. 1) ; the latter being synthesised by a modification of Ruhemann's method from 3-benzylidenepentane-2 : 4-dione which also was prepared by an improved method.4Methods applicable in the cinnoline series did not convert the corresponding chloro-compound (I; R = Cl) into the amine (I; R = NH,), but use of urea in a sealed tube gave reproducible yields. Treatment of the benzamido-compound (I; R = NH-COPh) with phosphorus oxychloride or phosphorus pentoxide in nitrobenzene at 180" did not give a useful product but some success was achieved with phosphorus pentoxide in boiling nitrobenzene. However, a melt of aluminium chloride and sodium chloride gave over 50% of the triazaphenanthrene (I1 ; R = Ph) . The fi-nitrobenzamido-derivative (I ; R = NH*CO*C,H,*NO,) was, however, cyclised in low yields by phosphorus pentoxide in nitrobenzene, other variations being useless.Quaternisation of 3-methyl-9-phenyl-1 : 2 : 10-triazaphenanthrene with methanolic methyl iodide yielded a mixture of two monomethiodides, but only one monomethiodide could be obtained from the 9-9-nitrophenyl analogue. These salts were inactive against the organisms listed in the preceding paper.or quinoline EXPERIMENTAL 3-Benzylidenepentane-2 : 4-dione.-A homogeneous mixture of benzaldehyde (4.0 moles, 404 c.c.), acetylacetone (4-0 moles, 424 c.c.), and piperidine (3.2 c.c.) was set aside at room temperature and shaken occasionally. After 6 days the mixture was diluted with ether (750 c.c.), and piperidine removed by washing with dilute hydrochloric acid followed by water. The ethereal layer was dried (MgSO,), the solvent removed, and the residue distilled, yielding unchanged materials followed by 3-benzylidenepentanedione (470 g. , 63% ; b. p. 149-150°/ca. 4 mm.). The semicarbazone separated from alcohol in glistening plates, m. p. 223-224" (decomp.
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