Carbozole

Likewise, the N derivatives of carbazoles undergo PFR [116-118], Upon irradiation in cyclohexane A-acetyl-carbazole (157) gives the following products (quantum yields in parentheses) [119] 1-acetylcarbazole (158) (0.10), 3-acetyl-carbozole (159) (0.09), and carbazole (160) (0.06) (Scheme 43). The analogous A-acetyldiphenylamine gives the ortho- and para-acetylated products along with diphenylaniline with quantum yields of 0.20,0.096, and 0.048, respectively [119], Table 10 shows that these values decrease from cyclohexane to ethanol, but less markedly than in the case of acetanilide (see Table 8). 

Vinblastine Vinblastine, [3aR-[3aa,4j3,5j3,5aj3,9(3R, 5S, 7R, 9S ),10bR, 13aa]]methyl-4-(acetyloxy)-9-[5-ethyll,4,5,6,7,8,9,10-octahydro-5-hydroxy-9-(methoxycarbonyl)-2//-3,7-methanoazacycloundecino- [5,4=b]indol-9-yl]-3a-ethyl-,4,5,5a,6,11,12,13a-octahydro -5-hydroxy-8-methoxy-6-methyl-17/-indolizino [8,l-cd]-carbozol-5-carboxylate (30.4.1),... 

Nazarov-like cyclization to give the carbozole tautomer 67. The latter undergoes a hydrogen shift and deprotonation to give the observed product. Typically, the isolated yields of carbazole are low because it reacts with nitrenium ion at the diffusion limited rate giving a poorly defined set of oxidized oligomeric products. Maximal yields of carbazole are obtained only when the reaction is carried out under highly dilute conditions. 

The structural formulas of the poly N-vinyl carbozole (PVC) and poly epoxypropyl carbazole (PEPC) are... 

The non-substituted compounds such as indols (e) or carbozoles (f) are typical nitrogen neutral compounds. 

CAN-mediated nitration provides a convenient route for the introduction of a nitro group into a variety of substrates. Alkenes on treatment with an excess of sodium nitrite and CAN in chloroform under sonication afford nitroalkenes. When acetonitrile is used as the solvent, nitroacetamidation occurs in a Ritter-type fashion. However, the attempted nitroacetamidation of cyclo-pentene-1 -carboxaldehyde under similar conditions resulted in the formation of an unexpected dinitro-oxime compound. A one-pot synthesis of 3-acetyl- or 3-benzoylisoxazole derivatives by reaction of alkenes (or alkynes) with CAN in acetone or acetophenone has been reported. The proposed mechanism involves a-nitration of the solvent acetone, oxidation to generate the nitrile oxide, and subsequent 1,3-dipolar cycloaddition with alkenes or alkynes. The nitration of aromatic compounds such as carbozole, naphthalene, and coumarins by CAN has also been investigated. As an example, coumarin on treatment with 1 equiv of CAN in acetic acid gives 6-nitrocoumarin in 92% yield. ... 

Figure 5.5 SERS spectra at %exc= 1064 nm of a SWNT film of about 100 nm thickness deposited on a rough Au support (curve 1) and composites obtained by the bulk polymerization of VK (0.5 g) in the presence of different amounts ofSWNTs 0.01 g (curve 2) and 0.1 g (curves). (Reprinted with permission from Polymer, Spectroscopic evidence for the bulk polymerization of N-vinyl carbozole in the presence of single-walled carbon nanotubes by M. Baibarac, I. Baltog, S. Lefrant and P. Gomez-Romero, 48, 18, 5279. Copyright (2007) Elsevier Ltd)...

The alkaloids imder discussion share a common Corynanthe-type nucleus derived from secologanin. Yohimbine is a carbocyclic variant of ajmalicine, and the enzymes that convert deglycosylated strictosidine to yohimbine have not been identified [124, 125]. Strychnine and bmcine are synthesized from the preakuammicine structure by hydrolysis, decarboxylation, and condensation reactions to aldehyde (Wieland-Gumlich), and subsequently reaction with acetyl-CoA to make a hemiacetal form of aldehyde (Wieland-Gumlich) and strychnine and brucine. Brucine is a dimethoxy form of strychnine. Ellipticine is a representative member of pyrido[4,3-b] carbozole alkaloid, and the formation of ellipticine is from ajmalicine (corynanthean skeleton) [126] (Fig. 20.8). 

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