Dibenzo carbazoles

As might be anticipated from the behaviour of the parent heterocycles, C-2 of indole, benzo[i]furan and benzo[i]thiophene (Table 13) is shifted to lower field than C-3. However, the shifts for C-2 (O, 144.8 Se, 128.8 S, 126.1 NH, 124.7 Te, 120.8) and C-7a (O, 155.0 Se, 141.3 S, 139.6 NH, 135.7 Te, 133.0) in the benzo[i] heterocycles vary irregularly (80OMR(l3)3l9), and the sequence is different to that observed for C-2 in the parent heterocycles, namely 0>Se>Te>S>NH. Also noteworthy is the upheld position of C-7, especially in indole and benzofuran, relative to the other benzenoid carbons at positions 4, 5 and 6. A similar situation pertains in the dibenzo heterocycles (Table 14), where not only are C-1 and C-8 shifted upheld in carbazole and dibenzofuran relative to the corresponding carbons in dibenzothiophene and fluorene, but similar, though smaller, shifts can be discerned for C-3 and C-6 in the former compounds. These carbon atoms are of course ortho and para to the heteroatom and the shifts reflect its mesomeric properties. Little variation in the carbon-hydrogen coupling constants is observed for these dibenzo compounds with V(qh) = 158-165 and V(c,h) = 6-8 Hz. 

Obige Reaktionen sind zur Herstellung partiell hydrierter Derivate von Alkaloiden mit Isochinolin-, Benzo-[a]-chinolizin-, Dibenzo-[a g]-chinolizin-, Benzo-fg]-indolo-[2,3-a]-chinolizin- und Pyrido-[4,3-b]-carbazol-Geriist vorteilhaft anwendbar11. 

Carbazole, A-methylcarbazole, IV-ethylcarbazole, dibenzofuran, dibenzothiophene, fluorene, dibenzo-p-dioxin, phenoxathiin, phenoxazine, phenothiazine, xanthene, biphenyl, naphthalene, phenanthrene, anthracene, and fluoranthene could be transformed by E. coli, [314] which was transformed using a plasmid bearing the carAa, Ac, and Ad genes, and expressing only the carA-encoded proteins. Further work is needed to develop a final biocatalyst and to prove the advantages that this degradative pathway would incorporate in a refining bioprocess. 

The currently accepted name for (1) in Chemical Abstracts is dibenzothiophene, although biphenylene, diphenylene, or biphenylylene sulfide are still used, especially in the Russian literature. Occasionally 9-thia-fluorene is used and recently, in one instance, dibenzo[6,d]thiophene. An alternative numbering system for (1) is met with on occasions in which C-4 is taken as C-1, as in carbazole. In the absenee of moleeular diagrams this system must be detected by reference to the chemistry described. For example, in a few dyestuff patents 2,7-diaminodibenzothiophene 5,5-dioxide is referred to and this is obviously the 3,7-diamino compound, also known as benzidine sulfone. 

Reddy, M. V., and K. Randerath. A comparison of DNA adduct formation in white blood cells and internal organs of mice exposed to benzo[a]py-rene, dibenzo[c,g]carbazole, safrole and cigarette smoke condensate. Mutat Res 1990 241(1) 37-48. 

Aromatic amines Benzo anthracenes Benzo fluoranthracenes Benzo pyrenes Benzoic acids Carbazoles Chrysenes Dibenzo thiophenes Fluorenes Imidazoles Indoles Naphthalenes... 

The benzo[a] (19), benzo[/t (15) and benzo[c] (16) fused heterocycles are heterocyclic analogues of naphthalene, with the dibenzo heterocycles (17) bearing a similar electronic relationship to phenanthrene. Some of these compounds are still known by their trivial names indole (15 Z = NH), isoindole (16 Z = NH), carbazole (18) and indolizine (19). The names thianaphthene and pyrrocoline for (15 Z = S) and (19) respectively are now little used. Particular confusion can arise in consulting... 

In the dibenzo heterocycles (Table 11), C-l and C-8 are shifted upfield in carbazole and dibenzofuran relative to the corresponding carbons in dibenzothiophene and fluorene, and similar, though smaller, shifts can be discerned for C-3 and C-6 in the former compounds. 

Most of the polymer modifications incorporating benzo-substituted pyrroles have been done with the dibenzo derivative, carbazole, primarily because of its well-known photocon-ductive properties. The modification reaction often involves a substitution reaction on some halogenated polymer. This substitution reaction can be quite facile. Poly(vinylbenzyl chloride), for example, reacts with the potassium salt of carbazole in DMF to yield the carbazole-functional polymer in 97% yield (76MI11110). 

A limitation to the use of modifiers in SFC has been the detector compatibility of the specific modifier. For example, most modifiers (i.e. methanol) provide a flame ionization detector response preventing use at a large concentration. In SFE, however, this limitation does not exist since modifiers can be used in a mixed mode with CCb and the sample. Figure 1 (taken from reference 25) shows an example of the use or modifiers in SFE. Here the comparison of extraction efficiencies obtained using CO and CO2 modified with methanol is shown. The matrices extracted in these SFE experiments were an XAD-2 sorbent resin and soils. The target analytes were dibenzo[a,i]-carbazole, diuron, 2,3,7,8-tetrachorodibenzo-p-dioxin (TCDD) and linear alkylbenzenesulfonate (LAS) detergent. For each of these respective analytes the extraction efficiency increased dramatically with the use of C02/methanol modifier compared to pure CO2 only as the extracting fluid. This was even the case for the ionic compounds namely, the linear alkylbenzenesulfonates (LAS), which were quantitatively recovered. 

Should we wish to allow for related multi-ring species (> three rings), there are also enthalpy of formation data for carbazole (XLIX), dibenzofuran (L) and dibenzothi-ophene (LI), some benzo and dibenzotetraazapentalenes (also called benzoannelated triazolotriazoles) (e.g., LH, LIII, both drawn without formal charges) [81] and their nitro derivatives [82], for 4-methyl-4//-a/a- (LIV) and 4-oxa-indene (LV) [83] (also called /V-methyl-azalene or 1-pyrindene, and oxalene, respectively), or more properly the 2,3 5,6-dibenzo derivatives thereof, and for 1,2,4,5-benzenetetracarboxylic dianhydride (LVI) [84], However, in the name of brevity we have decided not to discuss these benzoannelated species in this chapter. Instead, these await future analysis. 

DFT calculations on the intramolecular Diels-Alder reaction of penta-l,3-dienyl acrylates predict stereoselectivities that are in good agreement with the experimen- (g) tal results.85 Another DFT study at the B3LYP/6-31G(d) level of the intramolecular Diels-Alder cycloaddition of 5-vinylcyclohexa-1,3-dienes has been reported. Reaction rates are influenced by dienophile twisting and substituent effects.86 The intramolecular dehydro-Diels-Alder reactions of ynamides (79) provides a new synthesis of benzo[fc]-, tetrahydrobenzo[fc]-, naphtho[l,2-/j -, and dibenzo[a,c]carbazoles... 

Common Name Benzo[c,g]carbazole Synonym 7H-dibenzo[c,g]carbazole Chemical Name 7H-dibenzo[c,g]carbazole CAS Registry No 194-59-2 Molecular Formula C20H13N, C10H6NHC10H6 Molecular Weight 267.324 Melting Point (°C) ... 

Five-membered rings are also readily synthesized using this coupling methodology, enabling the production of dibenzo[M]fused heterocycles such as dibenzo-furans [2, 7], carbazoles [7, 8] (Scheme 1, G = O, NR respectively), and related compounds [8, 9]. Carbazoles are important structural motifs found in pharmaceuti-... 

Systems considered are the parent heterocycles with one heteroatom (furan, thiophene, selenophene, and pyrrole), their monoaza and polyaza derivatives, and the monobenzo derivatives of the above systems. Dibenzo derivatives such as dibenzofuran and carbazole are not taken into account, since they have no position in the five-mem bered ring susceptible to electrophilic attack. Likewise, no consideration is given to more complicated systems, formed by the fusion of two heterocyclic rings such as thienothiophenes or pyrrolopyridines, for which, in any case, no quantitative work is available. 

In practice, we have utilized it for the analysis of molecular systems comprised of 3 to 5 fused benzene rings. Our discussion in this document is limited to the following compounds phenanthrene, anthracene, fluoranthene, pyrene, benz(a)anthracene, chrysene, benzo(e)pyrene, benzo(a)pyrene, and dibenz(a,h)anthracene. The structures for these compounds are presented in Table I. It is important to note that the method has also been adapted to the determination of several other PAH compounds (e.g., benzo(c)phenanthrene, perylene, 3-methylcholanthrene, carbazole, 7H-dibenzo(c,g)carbazole, and indeno(l,2,3-cd)pyrene). 

The halogenation of dibenzo derivatives of five- and six-membered heterocycles presents a rather clear orientation pattern. The preference for substitution ortho and para to atoms having available electron pairs [e.g., phenoxathiin (26) and carbazole] reflects the stabilization... 

R. Goutarel, Bull. Soc. Chim. France pp. 769-774 (1960). Carbazoles (dibenzo[6,d]pyrrole), V-vinylcarbazole ... 

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