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

Abstract

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.

Mesomorphism Modulation of Perfluorinated Janus Triphenylenes by Inhomogeneous Chain Substitution Patterns

“…This synthesis route is simpler than standard used methods such as Suzuki cross‐coupling reaction, [58] Diels‐Alder cycloaddition reaction, [59] or photocyclodehydrofluorination (PCDHF), [36,37] as only two major steps are necessary, the reaction conditions are milder i. e. no need of expensive metal catalysts and oxygen‐free environment, the reagents used are cheap, and easily accessible, and the compounds easy to purify. Furthermore, the intermediates and target products are easily separated and purified, and obtained in yields greater than 70 %.…”

“…[34,35] Both p-BPn and m-BPn were reacted with butyl lithium [55][56][57] to yield the corresponding dilithium intermediates, which were then immediately reacted with perfluorobenzene (C 6 F 6 ) to yield the target fluorinated compounds, p-TPF4/6 and m-TPF4/6/8/10, or with 1,2-difluorobenzene (o-C 6 H 4 F 2 ) to yield the two non-fluorinated homologs, p-TP4 and m-TP4, respectively. This synthesis route is simpler than standard used methods such as Suzuki cross-coupling reaction, [58] Diels-Alder cycloaddition reaction, [59] or photocyclodehydrofluorination (PCDHF), [36,37] as only two major steps are necessary, the reaction conditions are milder i. e. no need of expensive metal catalysts and oxygen-free environment, the reagents used are cheap, and easily accessible, and the compounds easy to purify. Furthermore, the intermediates and target products are easily separated and purified, and obtained in yields greater than 70 %.…”