AN IMPROVED SYNTHESIS OF 5,5,9,9-TETRAMETHYL-5<i>H</i>, 9<i>H</i>-QUINO[3,2,1-DE]ACRIDINE

Fox, John L.; Chen, Chin H.; Stenberg, J. F.

doi:10.1080/00304948509355494

Cited by 5 publications

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“…In the subsequent C–N coupling reactions of 6 with 2,6-diaminotoluene and 1,3-diaminobenzene, a more reactive catalyst such as Pd(OAc) 2 /P( t -Bu) 3 is used ,, to provide tetraamines 7 and 8 , respectively. Quadruple ring closure of 7 in 85% phosphoric acid, via Friedel–Crafts-type electrophilic aromatic substitution, ,, gives ladder tetraamine 2 with nine collinearly fused rings in very good yields (90–95% per ring closure); from the analogous reaction of 8 in phosphoric acid (or 1:1 phosphoric/sulfuric acid mixture), only an “angular” tetraamine 5 is isolated in low yields . These results suggest that the “blocking” group, such as methyl group in 2 , is essential for the synthesis of collinearly fused oligo( m -anilines).…”

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confidence: 99%

Ladder Oligo(m-aniline)s: Derivatives of Azaacenes with Cross-Conjugated π-Systems

et al. 2012

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We describe the synthesis and electronic properties of ladder oligomers of poly(m-aniline) that may be considered as derivatives of azaacenes with cross-conjugated π-systems. Syntheses of ladder oligo(m-aniline)s with 9 and 13 collinearly fused six-membered rings employed Pd-catalyzed aminations and Friedel-Crafts-based ring closures. Structures were confirmed by either X-ray crystallography or correlations between DFT-computed and experimental spectroscopic data such as (1)H, (13)C, and (15)N NMR chemical shifts and electronic absorption spectra. All compounds have planar "azaacene" moieties. The experimental band gaps E(g) ≈ 3.5-3.65 eV, determined by the UV-vis absorption onsets, were in agreement with the TD-DFT-computed vertical excitation energies to the S(1) state. Fluorescence quantum yields of up to 20% were found. Electrochemically estimated HOMO energies of -4.8 eV suggested propensity for a facile one-electron oxidation and just sufficient environmental stability toward oxygen (O(2)). For two oligomers with "tetraazanonacene" moieties, potentials of E(4+/3+) ≈ 1.6-1.7 V vs SCE were determined for four-electron oxidation to the corresponding tetraradical tetracations.

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