Carbazole-like compounds

Use of excess oxidant leads to decomplexation and aromatization of the product. In the case of electron-rich aromatic products, oxidation can go further to quinone-like compounds. This has been used in the synthesis of carbazole natural products (Scheme 10.33)." " The substituted aniline 10.130 underwent electrophilic substitution by the iron complex 10.95. Regioselective oxidation to give a new i/-complex 10J12 allowed a second nucleophilic attack to generate the carbazole skeleton 10.133 in situ. Further oxidation resulted in decomplexation, aromatization of the ring to give carbazole 10.134 and some formation of iminoquinone 10.135. 

Further developments in this area have included the neparation of several additional N,N -diaryl indolo[3,2-h]carbazoles with substituents such as m-tolyl, ffi-anisoyl, or triarylamine-containing species. Like 221, these compounds, possessing excellent hole-transport properties, also occurred in stable amorphous states and displayed high glass-transition temperatures. LED devices involving these systems were also constructed and showed promising characteristics [OOSMO11-112)42]]. 

In rejecting claims 1-8 of Albrecht s application, the examiner noted that certain mono-basic esters of carbazole were reported to have powerful local anesthetic activity, whereas the corresponding dibenzofuran compounds were less effective. The further disclosure of the bis-basic dibenzofuran as having some minimal anesthetic activity was sufficient, the examiner alleged, to motivate a PHOSITA to make the bis-basic esters of the carbazole compounds like those claimed in Albrecht s application, since the prediction would be that the bis-basic ester of the carbazole would be a more effective anesthetic than the disclosed bis-basic dibenzofuran. It would, therefore, be obvious to make these compounds, and the claims should be rejected. 

Compounds like 267 and 269 exist as the valence tautomeric tetrazoles in the solid state, but (in part) as the azides shown in trifluoroacetic acid.316,318,322-324 The vastly improved yields of carbazole-type products... 

Polychloromethanes can take part in photochemical electron-transfer reactions with aromatic compounds, leading (in alcohol as solvent) to products with oxygenated one-carbon substituents. It is reported that ruthenocene (95), like ferrocene, gives the corresponding ethoxycarbonyl, formyl, or ethoxymethyl compounds when irradiated with carbon tetrachloride, chloroform, or dichloro-methane, respectively. Carbazole (96) behaves in a similar way with CCI4, and the... 

These include alkaloids and non-alkaloids that have phenolic functions in addition to a nitrogen atom. Even the alkaloids containing phenolic functions cannot be classified under one group. They may be phenyl alkyl amines, quinolines, isoquinolines, benzylisoquinolines [47-50], carbazole [51, 52] and others. However, they are included in this entry owing to their phenolic nature. Some of these compounds, like opium alkaloids, are of great medicinal importance. 

Carbazoles behave like o,o -disubstituted diphenylamines. However, the basicity of carbazole, pKa = —4.94, is much lower than that of diphenylamine (pfCo = 0.78), and also lower than that of indole and pyrrole. As a consequence, carbazole is insoluble in dilute acids but only soluble in concentrated H2SO4 with protonation of the N-atom. On pouring the solution into water, carbazole precipitates without polymerization. The N-H-acidity of carbazole (pfCA = 17.06) corresponds approximately to that of indoles and pyrroles. For this reason, carbazole is convertible into N-metalated compounds which can be subjected to electrophilic substitution on nitrogen. 

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