Synthesis and Characterization of Isodiphenylfluorindone and Isodiphenylfluorindinone

Heterocyclic Synthesis of Crowded Aposafranones: Structure of 1-Methyl-8-dimethylamino-10-phenylphenazin-2-(10H)one and Related Compounds

Oxidative condensation of three p-phenylenediamines with 3-hydroxy-2-methyl-N-(phenylamino)benzene gives new coloured aposafranones. 2-Methylresorcinol is easy to convert into the asymmetric building block 3-hydroxy-2-methyl-N-(phenylamino)benzene with aniline. The aposafranones are sterically crowded because of the 1-methyl and N-phenyl groups. The UV/Vis absorption maxima are in the range 530-545 nm.

Reactions of 4,5-difluoro-1,2-dinitrobenzene with amines in dimethylformamide or EtOH

Substitution reactions of 1,2-difluoro-4,5-dinitrobenzene were explored in dimethylformamide alone and with KOH/H2O, Hünig’s base or Et3N and with Me2NHCl/Et3N in EtOH. The fluorine atoms were always displaced in preference to the nitro groups. Three compounds were prepared from these studies and were characterised by X-ray single crystal structure determinations.

HFIP in Organic Synthesis

1,1,1,3,3,3-Hexafluoroisopropanol (HFIP) is a polar, strongly hydrogen bond-donating solvent that has found numerous uses in organic synthesis due to its ability to stabilize ionic species, transfer protons, and engage in a range of other intermolecular interactions. The use of this solvent has exponentially increased in the past decade and has become a solvent of choice in some areas, such as C-H functionalization chemistry. In this review, following a brief history of HFIP in organic synthesis and an overview of its physical properties, literature examples of organic reactions using HFIP as a solvent or an additive are presented, emphasizing the effect of solvent of each reaction.

5,11-Diazadibenzo[hi,qr]tetracene: Synthesis, Properties, and Reactivity toward Nucleophilic Reagents

5,11-Diazadibenzo[hi,qr]tetracene was synthesized as a new nitrogen-substituted polycyclic heteroaromatic compound by Pd-catalyzed cycloisomerization of an alkyne precursor followed by oxidative cyclization with bis(trifluoroacetoxy)iodobenzene. The substitution of imine-type nitrogen atoms significantly enhanced its electron-accepting character and facilitated the direct nucleophilic addition of arylamines under strongly basic conditions to afford the desired amino-substituted products. The introduction of amino groups induced a remarkable red-shift in their absorption spectra; the tetrasubstituted product exhibited intense near-infrared absorbing property. Furthermore, the π-electronic system, which includes a redox-active 1,4-diazabutadiene moiety, underwent reversible interconversion to its corresponding reduced form upon reduction with NaBH₄ and aerobic oxidation.

Highly Regioselective and Chemoselective [3 + 3] Annulation of Enaminones with ortho-Fluoronitrobenzenenes: Divergent Synthesis of Aposafranones and Their N-Oxides

A base-promoted unprecedented strategy for the regioselective and chemoselective divergent synthesis of highly functionalized aposafranones and their N-oxides has been developed from the [3 + 3] annulation of enaminones with o-fluoronitrobenzenenes. This novel synthetic strategy offers an alternative method for the construction of aposafranones and their N-oxides are meaningful in the fields of both biology and organic synthesis. The established protocol explores the annulation scope of enaminones, and it expands the application of nitro-based cyclization.

Stable Radical Cations of N,N'-Diarylated Dihydrodiazapentacenes

A series of quinoidal N,N'-diaryldiaza-N,N'-dihydropentacenes (Quino) was prepared in a two-step reaction, starting from quinacridone. Oxidation of Quino furnishes stable radical cations, isoelectronic to the radical anions of the azaacenes, whereas the dicationic species are isoelectronic to neutral azapentacenes. The spectroscopic properties of the diaryldiazapentacenes and their oxidized mono- and dications are equivalent to that of the dianion of tetraazapentacene (TAP), its radical anion and the neutral TAP.

First principles investigation of the spectral properties of neutral, zwitterionic, and bis-cationic azaacenes

An in-depth investigation of the optical properties of recently-synthesized linear azaacene derivatives of various electronic nature (neutral, dicationic, and zwitterionic) is presented.