Acenaphthylene, cyclization

The rate of dehydrocyclization increase with the number of aromatic rings in the molecule (19). The dehydrocyclization of alkylnaphthalenes can follow the same pathways as the cyclization of alkylbenzenes C5-dehydro-cyclization gives benzindans and benzindenes, while C6-dehydrocyclization yields anthracenes and phenanthrenes. In addition to these two pathways, a-substituted alkylnaphthalenes can cyclize to acenaphthenes and acenaphthylenes ... 

Related complexes of group 10 metals are accessible by an oxidative addition/reductive cyclization protocol, exploiting the inverse electron demand (Scheme 27) (Pt <2005JA13494>, Ni <20030M3604>). The nickel complex is thermally unstable, proceeding to perylene via a bimolecular reductive elimination or, in the presence of alkynes, delivering acenaphthylene derivatives by an insertion/reductive elimination pathway. 

The azonia derivative of acenaphthylene was obtained by two routes [84JCS(P1)2553], 4-Chloroquinolizinium salt (228) was reacted with diethyl sodiomalonate to afford diethyl quinolizin-4-ylidenemalonate (229). The quinolizine 229 was cyclized on treatment with refluxing nitrobenzene to afford cyclazinone 230 (75%), which was deethoxycarbonylated to give 231. l-Hydroxypyrrolo[2,l,5-c/e]quinolizinium salt (232) was prepared by treating the resulting cyclazinone 231 with perchloric acid. 

The ring-chain isomerisation of phosphino-substituted triazolo-pyridines was found to depend on the nature of the phosphine substituent. Conversion of the phosphines to their selenides resulted in a complete shift of the equilibrium towards electron-acceptor structure D (Scheme 10). Acenaphthene and acenaphthylene were converted to polycyclic phosphole derivatives via Ti(II)-mediated cyclization of the corresponding dialkynylated arenas. The related phosphole oxides were stable species (Scheme 11). Asymmetric lithiation of dimethyl-tert-butylphosphine sulfide and trimethylsilylation gave an intermediate that was subjected to a five-step reaction sequence including metallation, P-functionalization (in three steps) and removal of the silyl group to yield the precursor of Mini-PHOS (Scheme 12). ... 

Photocycloadditions are also exploited in the synthesis of fused polycyclic compounds. Tetracyclic (4-hetera)cyclopent[, c]acenaphthylenes can be synthesized by light-induced cycloaddition of 4-alk-l-ynylcoumarins to 2,3-dimethylbut-2-enes (Scheme 6.33). Addition of triplet-excited 4-alk-l-ynylcoumarin to the alkene affords the triplet biradical, which undergoes 1,5-cyclization to cyclopentenylcar-bene. The latter undergoes electrocyclic ring closure and [1,9]-H shift to yield the product [37]. 

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