Anellation

An interesting general synthesis using repeating anellation procedures has been developed by E. Vogel (W. Wagemann, 1978). First cyclohepta-3,5,7-triene-l,3-... 

As a consequence of the rigid face-to-face orientation, there are strong electronic interactions between the benzene rings in the dibenzo-anellated isodrin derivative. Irradiation with 254-nm UV light gave rise to a 7 3 equilibrium mixture of the educt with the [6 -I- 6]cycloaddition isomer. At an irradiation wavelength of 300 nm the cycloaddition wa completely reversed. 

The kekulene macrocycle consists of twelve anellated benzene rings and may be considered as an [iSlaanulene (inside) or a 30]annulene (outside). H. Staab (F. Diederich, 1978) called it a superbenzene , since it has the same symmetry as benzene. 

FIGURE 1.20 Rep roduction of a metabolic map. (Courtesy ofD. E. Nicholson, University of Leeds anel Sigma Chemical Co., St. Louis, MO.)... 

Adapted, from Jain, M., and Wagner, R. C., 1980. Introduction to Biolo cal Meinbrancs. New York Joim Wiley and Sons Martonosi, A., ed., 1982. Membranes anel Transport, Vol. 1. New York Plenum Press. 

AdapLed. from Brown, M., and GoldsLein, J., 1987. In Braunwald, E., eL al., eds., Harrison s Principles of Internal Medicine, 11th ed. New York McGraw-Hill and Vance, D., and Vance, J., eds., 1985. Biochemistry of Lipiels anel Meinbranes. Menlo Park, CA Benjamin/Cummings. 

The Diels-Alder reaction is the most important method for the construction of six-membered rings. For example it can be used as a step in a benzo-anellation procedure. The experimental procedure is simple, and yields are generally good side reactions play only a minor role. 

The unsaturated substituent in the carbene complex 1 often is aromatic or heteroaromatic, but can also be olefinic. The reaction conditions of the Dotz procedure are mild various functional groups are tolerated. Yields are often high. The use of chromium hexacarbonyl is disadvantageous, since this compound is considered to be carcinogenic however to date it cannot be replaced by a less toxic compound. Of particular interest is the benzo-anellation procedure for the synthesis of anthra-cyclinones, which are potentially cytostatic agents. ... 

Anelland, n. a ring joined to another by ortho fusion, anellated ring (see anellieren). anellieren, v.t. (Org. Chem.) join by ortho fusion" (as the two rings in naphthalene), aneUate. 

Anelliening, /. anellation (see anellieren). Anemoninsaure,/. auemoninic acid. Anemon-kampher, m. anemonin, -sSure, /. anemonic acid. 

New Diels-Alder reactions of 3-vinylindoles with an aryne selective access to functionalized [a]anellated carbazoles [145]... 

Pindur U., Lemster T. Recent Advances in the Synthesis of Carbazoles and Anellated Indoles With Antitumor Activity DNA-Binding Ligands and Protein Kinase C Inhibitors Recent Res. Dev. Org. Bioorg. Chem. 1997 1 33-54 Keywords Diels-Alder reactions of a 4,7-dioxo-indole with carbodienophiles... 

Gotoh, N., Graham, A., Niki, E. anel Darley-Usmar, V.M. (1993). Inhibition of glutathione synthesis increases the toxicity of oxidised LDL to human monoctites and macrophages. Biochem. J. 296, 151-154. 

Some heterocyclic amides, in principle similar to those described above, were shown to cyclize in a Michael type reaction to give anellated pyridones in excellent yield 1-1393... 

Hubener G, Lambacher A, Fromherz P (2003) Anellated hemicyanine dyes with large symmetrical solvatochromism of absorption and fluorescence. J Phys Chem B 107(31) 7896-7902... 

During the last 10-15 years, more emphasis has been on the development of new synthetic routes for obtaining variously substituted less common representatives and new varieties of CC- or C/V-anellated bicyclic diazaphosphole systems. CC-Anellation is possible in A, B, and D, out of which benzo anellated representative of only D has been reported. But, C7V-fused derivative of D is not reported, though... 

In the past, several general reviews on heterophospholes [2, 4-6] have covered the chemistry of diazaphospholes reported until early 1990s. Synthetic routes to different classes of diazaphospholes have been reviewed [7], Analogy between the synthesis of anellated diazaphospholes and their nonphosphorus analogs has also been reviewed [8], Some recent advances in the chemistry of anellated diazaphospholes made by our group have been included in a review on anellated azaphosp-holes [9], The reviews on the synthetic applications of phosphalkynes also describe the synthesis of diazaphospholes from these synthons [10-12], Present review aims to highlight and update important reports related to the chemistry of diazaphospholes which have mainly appeared during the last 15 years. 

Monocyclic 2H-[ 1,2,3 Idiazaphospholes (B) are easily accessible from the condensation of the four-membered chain incorporated in hydrazones or azoalkanes with phosphorus trichloride making available a large number of representatives that have been intensively studied [2, 4, 7], In contrast, their 1//-isomers (A) are less known and are obtained only as second minor product during the synthesis of 2//-[l,2,3]diazaphospholes in some cases. A facile synthesis for pyrido-anellated azaphospholes has been developed in our group by making use of 1,2-disubstituted pyridinium salts for condensation with phosphorus trichloride [8, 13-15], Accordingly, cyclocondensation of 2-alkyl-1-aminopyridinium iodides (1) with phosphorus trichloride in the presence of triethylamine affords pyrido-anellated l//-[l,2,3]diazaphospholes, i.e. l,2,3]diazaphospholo 1,5-a] pyridines (2) (Scheme 1) [16],... 

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