Phenalene

Heteroeyeles structurally based on the phenalene ring system form an interesting elass, frequently possessing distinetive eolours. With nitrogen as the central atom we have the unstable 9b-azaphenalene (24), whieh has only fairly reeently been prepared and is still comparatively little studied (76JCS(Pl)34l). The cyclazine nomenclature is commonly applied to this and related compounds thus, (24) is (3.3.3)cyclazine. With further aza substitution, in positions alternant to the central atom, their stability increases the heptaazaphenalene (25) is (thermally) a very inert compound, derivatives of which, e.g. the triamine, have been known since the early days of organic chemistry (see Chapter 2.20). 

A related diazotization reaction involving the supposed peri-aminolepidine (357) to give the unknown phenalene type system (297) was later shown to be incorrect due to wrong orientation of the amino substituent (42JA2417). 

The hydrocarbon phenalene is the precursor of both a highly stabibzed anion and a highly stabilized cation. The Huckel MO diagram is shown in Fig. 9.7. The single orbital at the nonbonding level is the LUMO in the cation and the HOMO in the anion. The stabilization energy calculated for both would be the same and is 0.41/3 by the HMO comparison. ... 

The orbital coefficients for the MO of energy a for the phenalenyl system described in Fig. 9.7 are as shown below. Predict the general appearance of the NMR spectra of the anion and cation derived from phenalene. 

Lithiuin-9-hydrido-perhydro-9b-borata-phenalen(I)6 wird zur stereoselektiven Reduktion cyclischer und bicyclischer Ketone herangezogen (weiteres s.S.335) ... 

Trimethyl-phenalenium-perchlorat wird durch Lithiumalanat in Diathylather mit 93%iger Ausbeute zu 3,6,9-Trimethyl-phenalen reduziert6. 

Not all fused systems can be fully aromatic. Thus for phenalene (37) there is no way double bonds can be distributed so that each carbon has one single and one double bond. ° However, phenalene is acidic and reacts with potassium methoxide to give the corresponding anion (38), which is completely aromatic. So are the corresponding radical and cation, in which the resonance energies are the same (see p. 55). ° ... 

E.s.r. showed that, X. ray irradiation of tetraalkyldiphosphine diphosphides gave phosphoranyl radicals with t.b.p. structures (39).114 A structure has been assigned to phosphiny1hydrazy1s (40). The dimethy1 ami no radical was particularly persistent.115 The e.s.r. parameters of the electrogenerated pyrazine radical cations (41) have been recorded.116 The spectra of a stable furanyl phosphate radical adduct117 and a phenalene radical anion which involves injection of spin density into half an attached cyclophosphazene ring,11 are reported. 

The first observation of carbon acid participation in the alkaline hydrolysis of esters was reported in 1970 by Bowden and Last (1970, 1973b). The 8-acetyl-, 8-propionyl- and 8-isobutyryl-l-naphthoates [43] reacted rapidly in aqueous dioxan containing an excess of base. However, the immediate products of these reactions are the phenalene-l,3-diones [44], The two... 

A third alkaloid of this type, chilocorine B (20), was isolated from C. cacti. In this molecule, NMR experiments showed that the 2-methylperhydro-9i -aza-phenalene and the 3,4-dimethyloctahydro-8b-azaacenaphtylene subunits are linked in a spirocyclic fashion. An X-ray diffraction analysis fully determined the structure and relative stereochemistry of this alkaloid [34]. 

---