Diels-Alder Cycloaddition with CO, CO2, SO2, or N2 Extrusion: A Powerful Tool for Material Chemistry

Phenyl, naphthyl, polyarylphenyl, coronene, and other aromatic and polyaromatic moieties primarily influence the final materials' properties. One of the synthetic tools used to implement (hetero)aromatic moieties into final structures is Diels-Alder cycloaddition (DAC), typically combined with Scholl dehydrocondensation. Substituted 2-pyranones, 1,1-dioxothiophenes, and, especially, 1,3-cyclopentadienones are valuable substrates for [4 + 2] cycloaddition, leading to multisubstituted derivatives of benzene, naphthalene, and other aromatics. Cycloadditions of dienes can be carried out with extrusion of carbon dioxide, carbon oxide, or sulphur dioxide. When pyranones, dioxothiophenes, or cyclopentadienones and DA cycloaddition are aided with acetylenes including masked ones, conjugated or isolated diynes, or polyynes and arynes, aromatic systems are obtained. This review covers the development and the current state of knowledge regarding thermal DA cycloaddition of dienes mentioned above and dienophiles leading to (hetero)aromatics via CO, CO2, or SO2 extrusion. Particular attention was paid to the role that introduced aromatic moieties play in designing molecular structures with expected properties. Undoubtedly, the DAC variants described in this review, combined with other modern synthetic tools, constitute a convenient and efficient way of obtaining functionalized nanomaterials, continually showing the potential to impact materials sciences and new technologies in the nearest future.

Synthesis of diverse heterocyclic frameworks using cyclopentadienones via the Diels–Alder strategy

In this review article, we briefly summarize the versatility of Diels–Alder reactions of cyclopentadienones and concise routes to diverse hetero-atom bearing PAHs using cyclones as building blocks.

Deep-cavity subporphyrazines with extended π-perimeters

Unprecedentedly large subporphyrazines (SubPz) with dibenzoquinoxalino-fusion and peripheral phenyl substitution were prepared by the cyclization of perfluorated or non-fluorous polyphenyl-substituted quinoxaline dinitriles and characterized by spectroscopic techniques. The compounds suitability to act as photosensitizers was explored by wavelength-specific induction of singlet oxygen luminescence and was shown to be excellent. Determination of 1O2-quantum yields suggests that fluorine substitution enhances the photosensitization efficiencies of the SubPz. On the other hand, cyclic voltammetry reveals an increase of irreversible reductive processes in case of the fluorinated SubPz.

Systematic investigation of phthalocyanines, naphthalocyanines, and their aza-analogues. Effect of the isosteric aza-replacement in the core

A series of zinc complexes of phthalocyanines, naphthalocyanines and their aza-analogs was studied and compared using UV-vis and MCD spectra, molecular calculations, and photophysical and electrochemical measurements.