Acenaphthene, 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 ... 

Occasional formation of such salts in a small amount on nitration of compound 1, e.g. with N2O4 in 1,2-dichloroethane, indicates that the process could be initiated with common oxidants47. However, a question arises here as to why a similar cyclization is not observed for acenaphthene sponges (cf. Scheme 22) The answer may be that the N N distance in these sponges is remarkably longer (Table 4) and thus the cyclization becomes unfavourable. That the double proton sponge 35 with an N N distance yet shorter than 1 (Table 4) is very prone to cyclize to dihydroperimidinium salts44,64,137, confirms this explanation (Section IV.B.8). 

Condensed and other carbocyclic systems Condensed heterocycles have been prepared either directly or via a condensation product. Acenaphthen (23) reacted with 10 in the presence of AICI3/HCI to yield iminium salt 24. Tetralones 25 were condensed with 10 and cyclized subsequently in polyphosphoric acid to yield 26 ... 

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). ... 

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