Poly cyclic

Nitration and aromatic reactivity D The nitration of hi- and poly-cyclic compounds... 

Polycyclic aromatic hydrocarbons undergo electrophilic aromatic substitution when treated with the same reagents that react with benzene In general polycyclic aromatic hydrocarbons are more reactive than benzene Most lack the symmetry of benzene how ever and mixtures of products may be formed even on monosubstitution Among poly cyclic aromatic hydrocarbons we will discuss only naphthalene and that only briefly Two sites are available for substitution m naphthalene C 1 and C 2 C 1 being normally the preferred site of electrophilic attack... 

Part 2 (Volumes 2 and 3) deals with mono- and poly-cyclic compounds with one or more six-membered heterocyclic ring, with nitrogen, oxygen and sulfur as the heteroatoms. Volume 2 contains the six-membered rings with one nitrogen atom (Part 2A) and Volume... 

Reggelin et al. reported the application of methylated, enantiomerically pure acyclic and cyclic 2-alkenyl sulfoximines 203 for the synthesis of highly substituted aza(poly)cyclic ring systems 204 under complete stereocontrol <06JA4023 06S2224>. 

GUNDERSON AND THRANE Poly cyclic Aromatic Hydrocarbons... 

Electron-deficient heteroaromatic systems such as 1,2,4-triazines and 1,2,4,5-tetrazines easily undergo inverse electron demand Diels-Alder (lEDDA) reactions. 1,2-Diazines are less reactive, but pyridazines and phthalazines with strong electron-withdrawing substituents are sufficiently reactive to react as electron-deficient diazadienes with electron-rich dienophiles. Several examples have been discussed in CHEC-II(1996) <1996CHEC-II(6)1>. This lEDDA reaction followed by a retro-Diels-Alder loss of N2 remains a very powerful tool for the synthesis of (poly)cyclic compounds. 

Intramolecular variants of this reaction are often utilized in the synthesis of (poly)cyclic systems, while the intermolecular variant of the transformation is the key step in one of the most frequently studied and utilized carbon-carbon bond forming reactions, the Heck reaction (for details see Chapter 2.2.). 

The epoxide of bromobenzene is one such toxic intermediate, and this example is discussed in more detail in chapter 7. In the case of some carcinogenic poly cyclic hydrocarbons such as benzo[a]pyrene, however, it seems that the dihydrodiol products are in turn further metabolized to epoxide-diols, the ultimate carcinogens (see chap. 7, Figs. 7.2 and 7.3). 

Synthesis of TVi- and Poly-cyclic Ring Systems without Ring Junction Heteroatoms 657... 

For a homoaromatic system, surface delocalization in the cyclopropyl ring is perpendicular to the bridging bond, thus forming a Hiickel aromatic electron ensemble which is delocalized in just one part of the bi(poly)cyclic system. 

A new active-iron reducing system - iron(II) chloride tetrahydrate-excess lithium powder-5 mol% 4,4 -di-f-butylbiphenyl in THF - reduces ketones and imines.326 (g) Mono- and poly-cyclic ketones in particular are reduced with good to excellent ee. 

Directed metalation using alkali metal-mediated zincation has been developed for mono- and poly-cyclic aromatic derivatives.100,101... 

The Preparation of Diamonoid Substrates by the Rearrangement of Poly cyclic Hydrocarbons... 

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