Fused Ring Systems Involving Pentafulvene Moieties

Fused Ring Systems Involving Pentafulvene Moieties 

Fully conjugated polycyclic systems involving pentafulvene moieties, such as azulene 4, pentalene 5, and indacene 6, have attracted much attention due to their novel properties. Recently, higher oligoacenes such as rubrene 246 and pentacene 

Pseudoazulenes 250 and 251 are Jt-isoelectronic with azulene 4, where the lone pair of electrons of a heteroatom in the six-membered ring is formally derived from one of double bonds at the seven-membered ring of the azulene skeleton. Therefore, these compounds should exhibit similar but specific properties in relation to azulene. Recently, it has been shown that a 5//-cyclopenta[c]quinolone derivative displays moderate-to-high inhibitory activity against cancer cells. This possible biological importance renewed interest in this class of compounds. Because some old reviews summarize the synthesis and the chemistry of pseudoazulenes [147], this section describes new synthetic methodologies published in the past two decades only. Because new azulene syntheses published during the past two decades are discussed in Sections 6.3.1.2 and 6.4.1, this section skips the azulene chemistry. 

The last part of this section concentrates on the synthesis of fuUerene fragments possessing fulvalene it-systems. Recent advances in fuUerene chemistry have attracted much interest in bowl-Uke polycyclic aromatic hydrocarbons (PAHs) 

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Fused Ring Systems Involving Pentafulvene Moieties... 

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