Azuleno azulenes

Arylbenzotriazoles (797) are prepared via 2-nitro- and 2-amino-diphenylamines (Scheme 161). The 2-nitrodiphenylamines (796) are prepared from the appropriate aniline by reaction with 2-fluoronitrobenzene in the presence of KF <808215,85JCS(Pl)2725>. Azo-coupling of 2-amino-1-cyano-azulene (798) with p-tolyldiazonium chloride gives (799) (Scheme 162). Catalytic reduction of (799) quantitatively yields the diamino derivative (800), which on diazotization affords 9-cyano-azuleno[l,2-J]triazole (801) in 77% yield <85TL335>. 

The azulene-pyridazine derivative 423 has been obtained by attachment of a seven-membered carbocycle to cyclopentadieno[pyridazine derivatives have been similarly obtained (78H387). As for other peri-annelated heterocycles with... 

Over the years, a number of [njcyclophanes based on polycyclic aromatic hydrocarbons have been prepared [16]. However, the absolute limits to which any of these systems can be bent has not been systematically investigated. Hafner s [n](l, 6)- (15) and [ ](2, 6)azuleno-phanes (n = 11-13, 16) are a promising step in this direction [17]. They were produced by an intramolecular azulene-forming reaction of the 4 - (co-cyclopentadienylalkyl)-1 -methy Ipyridinium salts 14 (Scheme 5). The crystal structure of... 

In an analogous manner, we succeeded finally in synthesizing the 5-carbonitrile of the kata-condensed tetracyclic azuleno(l, 2-f)azulene (776) in a 50% yield by condensation of (44) with azulene-2-acetonitrile (149) to the red-violet aminonitrile (174) and smooth thermolysis of it78. The hydrocarbon (176) is the first known member of the theoretical 12 isomeric azulenoazulenes of which considerable stability and aromatic properties are predicted79. Indeed, (7 76) can readily be formylated by dimethylformamide-phosphorylchloride in a typical aromatic-electrophilic substitution to the 1-carbaldehyde (7 77)78. ... 

Aza-azuleno[2,l-b] thiophen has been prepared from 2-chloro-3-formyl-l-aza-azulene by annelating the thiophen ring by the Fiesselmann reaction. ... 

A modified mechanism for the formation of the cycloheptafuranone (83) by pyrolysis of phenyl propiolate (82) has been proposed.The action of copper(I) phenylacetylide on the azulene ester (84) leads to the azuleno[2,l-Zi]furan(85). 2 ... 

A cyclization that involves a 1,2-diarylethane system is the intramolecular reaction of the bridged azulene-benzene compounds (151), which gives, after dehydrogenation, azuleno[l,2,3-cfi( phenalenes. The initial product is said to be a... 

Structures comprising Two Five-Membered Rings and One Seven-Membered Ring (5,5,7).—Azuleno[2,l-d]thiazoles [C3NS-CS-C7]. The reaction between the substituted azulenes (171 R = H or C02Et) and neutral or basic alumina gives the title compounds (172). ... 

Aza-azuleno[2,3-d]thiazoles [C3NS-C4N-C7]. The reaction between 3-thiocyanato-2-amino-l-aza-azulene and acetic anhydride gives (173 R = Ac), which can be hydrolysed to (173 R = H)/ ... 

The phosphorescence and fluorescence spectra of compound (23) have been recorded <89CBi 119>. The electronic and fluorescence spectra have been measured for azuleno[l,2-f>]furan (144), which is an iso-/7-electron system of benz[a]azulene and presents anomalous fluorescence from the second excited singlet state, as does azulene <87SA(A)1377). Fluorescence spectral properties of a series of 2-(4-substituted phenyl)benzofurans have been investigated to determine their applicability as organic reagents for analysis <85bcj2192>. 

On a partially analogous route adduct 151, obtained by trapping 5,6-didehydroazulene (from 150) with furan, is transformed by means of tetrazine 148 to stable azuleno[5,6-c]furan 152. Both azulenes 149 and 152 can be characterized as adducts (see Section 4.5.3). 

Furans. Aminoazulene 163b (Scheme 39) can be obtained from jS-dolabrin (163a) by Nozoe s azulene synthesis. Deamination is accompanied by furan-ring closure to yield azuleno[6,5- ]furan 164 and, after defunctionalization, compound 165 (61C1L1715). 

Pyridines. Azuleno[l,2-b]pyridone (214 Scheme 49) forms in the vacuum pyrolysis of 3-ethynyl-2-phenylpyridine (213) as a by-product (02EJO254 . Azuleno[l,8-cd]pyridinedione 216 similarly occurs as a minor by-product on irradiating the bridged dihydronaphthalene 215 (a tetraenic propellane) to form tetracyclodecadienes by an electrocyclic reaction (69ISJ435). The formation of azulene 216 involves dehydrogenation. 

Pyridazines. Hafner et al. (78H(11)387) used variants of their azulene synthesis to construct azuleno[8,l-cd]pyridazines by... 

A two-step [4+2] cycloaddition of azulene or 1-nitroazulene and the extremely electron-deficient diazadiene system of tetrazine 221 (Scheme 51) yields, together with other substances, azuleno[l,2-d]pyr-idazines 222a and 222b (93AP29). 

The stability of azuleno[l,2-l ]- and azuleno[2,l-fc]thiophene (45a and 69, respectively) is comparable to that of benz[a]azulene because the computed heats of formation of all three of them range from about 102 to 104kcal/mole (83JF2,1155). In the groups of simple iso-7t-electronic azuleno[l,2-b]-, azuleno[2,l-fc]-, and azuleno[l,2-c]azoles, the stability has been predicted to decrease in the order of fused (benzene >) pyrrole > thiophene > furan, that is in the order of the stabilities of the heterocyclic moieties (87H(26)2025). Non-functionalized azuleno[6,5-b]pyrrole 195 is... 

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