Synthesis of dibenzosuberenone-based novel polycyclic π-conjugated dihydropyridazines, pyridazines and pyrroles

Abstract

The synthesis of novel polycyclic π-conjugated dihydropyridazines, pyridazines, and pyrroles was studied. Dihydropyridazine dyes were synthesized by inverse electron-demand Diels–Alder cycloaddition reactions between a dibenzosuberenone and tetrazines that bear various substituents. The pyridazines were synthesized in high yields by oxidation of dihydropyridazine-appended dibenzosuberenones with PIFA or NO. p-Quinone derivatives of pyridazines were also obtained by H-shift isomerization following the inverse electron-demand Diels–Alder reaction of tetrazines with p-quinone dibenzosuberenone. Then these pyridazines were converted to the corresponding pyrroles by reductive treatment with zinc. It was observed that all the dihydropyridazines obtained gave absorbance and emission at long wavelengths.

Synthesis and Properties of Azahomocorannulenyl Cations and Radicals

“…Herein, we report on the synthesis and properties of azahomocorannulene derivatives 2, [32][33][34] in which one of the hexagons in the corannulene core of 1 is substituted by a heptagon ring. With the introduction of the heptagon ring, it acquires a 2-azaazulene structure [35][36][37] in its center, which is a non-alternant structure of 2-azanaphthalene. This study presents rare examples of a polycyclic aromatic tropylium cation and tropyl radical.…”

Dibenzosuberenone-Based Photo- and Thermochromic Switches, a Transformation: Rearrangement of Dibenzosuberenones to Spiro Anthrones

“…determined by comparison with the data in our previous study. 36 The chemical structures of the spiro anthrones were determined by NMR spectroscopy, UV−vis spectroscopy, and HRMS analyses. When the HRMS spectra of 3a and 4a are compared, it is seen that their masses are the same.…”

“…In our previous studies, fluorescent compounds 3a – g were synthesized and their fluoride sensor and photophysical properties were examined. In addition, these compounds were oxidized to pyridazines 5a – g and then converted to pyrrole derivatives with Zn. , In the present study, the behavior of 3a – g under heat and visible light (420 nm) stimulants was examined. When these molecules (50 mg, ∼10 –3 M) were refluxed in toluene (100 mL), it was observed that dihydropyridazine-appended dibenzosuberenone derivatives with central seven-membered rings quantitatively underwent rearrangement to spiro anthrones with central six-membered rings (Scheme ).…”

“…When switches 3a – g were directly irradiated in the NMR tube with visible light (420 nm) in a Rayonet RPR-200 photochemical reactor, it was observed that 3a – d , f rearranged to spiro 4a – d , f with >99%, >99%, 84%, 32%, and 16% conversions, respectively (Table ). 3e , g did not rearrange to spiro 4e , g but were oxidized to 5e and 5g with 11% and 17% conversions, respectively. When 3a – g were irradiated for a longer time, there was no change in 3a , b , but oxidation from 3c – g to 5c – g increased.…”

“…When 3a – g were irradiated for a longer time, there was no change in 3a , b , but oxidation from 3c – g to 5c – g increased. The structures of 5c – g were determined by comparison with the data in our previous study …”