Dibenz acridine

Dibenz[ ,fc]acridine, I Dibenz[ ,/ acridine, II 7W-Dibenzo[c,g]carbazole, III... 

Diaminoanisole sulfate 4,4 -Diaminodiphenyl ether 4,4 -Diaminodiphenylmethane 4,4 -Diaminodiphenylmethane dihydrochloride 4,4 -Diaminodiphenyl sulfide ds-Diamminedichloroplatinum Dibenz[<2,li]acridine Dibenz[ ,/]acridine Dibenz[<2,li]anthracene 7//-Dibenzo[< g]carbazole Dibenzo[ ,e]pyrene Dibenzo[ ,li]pyrene... 

A detailed study of the dehydrogenation of 10.1 l-dihydro-5//-benz[6,/]azcpinc (47) over metal oxides at 550 C revealed that cobalt(II) oxide, iron(III) oxide and manganese(III) oxide are effective catalysts (yields 30-40%), but formation of 5//-dibenz[7),/]azepinc (48) is accompanied by ring contraction of the dihydro compound to 9-methylacridine and acridine in 3-20 % yield.111 In contrast, tin(IV) oxide, zinc(II) oxide. chromium(III) oxide, cerium(IV) oxide and magnesium oxide arc less-effective catalysts (7-14% yield) but provide pure 5H-dibenz[b,/]azepine. On the basis of these results, optimum conditions (83 88% selectivity 94-98 % yield) for the formation of the dibenzazepine are proposed which employ a K2CO,/ Mn203/Sn02/Mg0 catalyst (1 7 3 10) at 550 C. 

Nitroso-5//-dibenz[/>,/]azepine (9, R = NO) is relatively stable to photolysis under argon, whereas in benzene solution in the presence of oxygen, irradiation induces an oxidative Fischer -Hepp-type rearrangement to 2-nitro-5//-dibenz[6,/]azepinc (10, R = N02), accompanied by ring contraction to acridine-9-carbaldehyde184 (see also Section 3.2.2.4.). 

Oxidation of 5//-dibenz[7>,/]azepine (12) with Fremy s salt [ON(S03K)2] yields a mixture of acridine-9-carbaldehyde (13) and 2//-dibenz[A,/]azepin-2-one (14).215 The dibenzazepin-2-one 14 is also obtained in 46% yield with bis(trifluoroacetoxy)pentafluoroiodobenzene [PhI(OCOCF3)2] in acetonitrile as the oxidant.221... 

The ring expansions of acridine derivatives to dibenz[/j, / ]azcpines (see Section 3.2.1.4.1.5.) are reversible in hot mineral acid.29 161-184 227 For example, 5-acetyl-52/-dibcnz[/j./]azcpine (1) in refluxing 48% hydrobromic acid furnishes 9-methylacridine (2).29... 

Nitroso-5//-dibenz[/j,/ azepine (see Section 3.2.1.5.4.1.) in methanolic hydrochloric acid undergoes rearrangement and ring contraction to a mixture of acridine (59%), acridine-9-carbaldehyde (trace), and 2-nitro-5//-dibenz[/ ,/ azepine (3% mp 176-178 C).184 However, in acetone and hydrochloric acid, the aldehyde (57 %) becomes the major product. On thermolysis, (or photolysis in the presence of oxygen), in hydroxylic solvents, the nitroso compound yields mainly acridine (36-76%) together with minor amounts of either 2-nitrodibenzazepine (4-6% by thermolysis) or acridine-9-carbaldehyde (18% by photolysis). However, in non-hydroxylic solvents, e.g. cumene, acridine-9-carbaldehyde (64%) is the major product. 

A nitrenium ion is thought to be involved in the facile and almost quantitative (94%) conversion of 5//-dibenz[6,/]azepine to acridine in the presence of silver(I) trifluoroacetate in dichloromethane at 20 C.228... 

Acridine-9-carbaldehyde (24%) is one of several products formed from the oxidation of 5//-dibenz[A/]azepine with tert-butyl hypochlorite in dichloromethane at — 70 C.229 The reaction is even more complex in the presence of silver(I) trifluoroacetate, and an analysis of the reaction mixture by GC-MS techniques reveals the presence of eleven products, the major ones being acridine (37%), an unidentified 5//-dibenz[/ ,/]azepinecarbaldehyde (23%) and acridine-9-carbaldehyde (9 %). 

The first reported derivative of 1,2-oxazepine was dibenz[f,/][l,2]oxazepine-ll-carbonitrile (3 a). This, together with small amounts of compounds 4 and 5, is formed when acridine-9-carbonitrile 10-oxide (la) is irradiated with UV light,6,7 It is likely that the reaction proceeds by way of the oxaziridine valence tautomer 2a, which, however, was not detected.7 Photo-isomcrization of 9-chloroacridine 10-oxide (lb) yields the 11-chlorodibenzoxazepine 3b.6,7... 

Dibenz[c,/][1,2]oxazcpine-ll-carbonitrile isomerizes to the TV-oxide acridine-9-carbonitrile 10-oxide on heating in aprotic solvents. Attempted chromatography on silica gel or alumina columns gave a mixture of the oxepino[2,3-6]quinolinecarbonitrile 2, the oxoazepinoindolecarbo-nitrile 3 and the benzo[c]-2-aza-l,6-oxa[10]annulenecarbonitrile 4. Only these types of compounds were isolated when 2,7-dimethylacridine 10-oxide was irradiated.6... 

Dibenz(ay]acridine deep blue pale blue deep blue pale blue... 

The methine bridge in acridines can be derived from dihalomethanes. Originally sodium carbonate was used, with dichloro- or diiodo-methane, to prepare dibenzacridine (624) from 2-naphthylamine (02JCS280). Subsequently, better yields were obtained when dichloromethane, 1,1-dichloroethane or benzal chloride, 1-naphthylamine, and a solvent were heated, the products being dibenz(c,/z jacridines (624) (06JCS1387). 

This rearrangement, however, is complex and further studies show it to be dependent on temperature, solvent, pH and, most importantly, the absence or presence of oxygen. A similar overall mechanistic scheme operates for the acid-catalyzed rearrangement of A/-nitroso-5//-dibenz[6,/]azepine to acridine derivatives e.g. acridine-9-aldehyde) (74CRV101). 

Oxidation of 5//-dibenz[6,/]azepines by Fremy s salt has been examined closely. At pH 7.5 the quinonoid dibenz[6,/]azepin-2-one is produced together with acridine-9-aldehyde (74CRV101). 3-Chloro-10,11 -dihydro-5//-dibenz[6,/]azepine yields a mixture of the quinoneimines (174 R=C1) and (175) which with sodium dithionite reduce to the corresponding chlorohydroxydihydrodibenzazepines (76JHC269). 

The unstable dibenz[c,/][l,2]oxazepines (312 R = CN, Cl) have been isolated as the major products of the UV irradiation of 9-cyano- and 9-chloro-acridine 10-oxides (310) in benzene (c/. the analogous Af-imide to 1,2-diazepine conversion on p. 598). Although none of the oxaziridine tautomer (311) was detectable by UV spectroscopy, the subsequent deoxygenation of (312) to acridine suggests the existence of a thermal equilibrium between (311) and (312) (79T1273). These dibenzo compounds (312) are the only fully unsaturated oxazepines yet isolated but the 2,3-benzoxazepin-l-one system (314) has recently been prepared by the reaction of benzonitrile oxide with the benzopyranone (313) (80JCS(Pl)846). 

See Fig. 9 for data on benz[a]acridine, benz[c]acridine, naphtho[2,3- ]quinoline, naphth[2,3- ]iaoquinoline, benz[6]acridine, dibenz[6,fe]acridine, see ref. 7. 

Unstable dibenz[c,/ [l,2]oxazepines (73 R = CN, Cl) are major products of the UV irradiation of 9-cyano- and 9-chloro-acridine 10-oxides (71) in benzene. No oxaziridine tautomer (72) was detectable by UV spectroscopy. 

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