Cinnolines, 1,4-dihydro- from

Cinnoline, 4-alkylamino-3-phenyl-tautomerism, 3, 5 Cinnoline, 4-amino-biological aaivity, 3, 56 nitration, 3, 21 tautomerism, 3, 5 Cinnoline, dihydro-N-aminoindoles from, 4, 361 Cinnoline, 3,4-diphenyl-synthesis, 3, 42 Cinnoline, 3-hydroxy-synthesis, 2, 92 tautomerism, 3, 4 Cinnoline, 4-hydroxy-tautomerism, 3, 4 Cinnoline, 4-methyl-nitration, 3, 21... 

Phenyllithium adds to the N=N bond of benzo[c]cinnoline giving, on work-up, the air-sensitive, 5,6-dihydro-5-phenylbenzo[c]cinnoline (53). In an attempt to generate the radical corresponding to triphenylhydrazyl from 53, Wittig and Schumacher S found that oxidation with silver oxide or lead tetraacetate produced instead the quinonimine 54, analogous to the product formed by methylating 2-hydroxybenzo[c]cinnoline (Section V,D). On reductive acetylation, the quinonimine is converted into the 5,6-dihydro... 

Diethyl 1 -phenyl-1 a,7b-dihydro- [ 1 H -cyclopropa [c] cinnoline-1,1 a-dic arboxylate (194) gave a separable mixture of ethyl 4-(a-ethoxycarbonylbenzyl)-l,4-dihydro-3-cinnolinecarboxylate (195) and ethyl 3-cinnolinecarboxylate (196) (AcOH, reflux, 30 min 40% and 5%, respectively, after separation from... 

Aza-heterocycle Ring Contraction. A variety of polyaza six-ring heterocycles undergo contraction with formal excision of N, e.g. eq 14. Further heteroatoms in the ring are tolerated 1,2,3-triazines yield pyrazoles and 1,2,4-triazines yield imidazoles, with the latter usually requiring reflux temperature. The utility of indole syntheses from cinnolines " by this method should be noted. Adj acency of heteroatoms is not required conversions of pyrimidine to pyrrole and 1,3,5-triazine to imidazole have been recorded. The mechanism of these conversions is unclear, but ring dihydro derivatives are thought to be involved. 

To a suspension of 1 g of 4,5-dihydro-lH,3H-l-benzazocine-2,6-dione in 20 mL 1,2-dimethoxyethane and 0.1 mL water was added 0.84 g freshly prepared n-butyl nitrite. Hydrogen chloride gas was bubbled through the mixture at 25°C for 5 min the resulting solution was stirred overnight at room temperature, after which time the intermediate diazonium chloride usually had separated. The solution or suspension was diluted with 10 mL water, the mixture was warmed for 5 min on a steam bath, and the resulting suspension was filtered. The solid residue was crystallized from aqueous ethanol to give 4-0X0-l,4-dihydro-cinnolin-3-ylpropionic acid, in a yield of 61%, m.p. 226-228°C. 

Benzo[c]cinnolines from 9,10-dihydro-9-aza-10-boraphenanthrenes s. 19, 541 Sodium salt Na ... 

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