Angelika Mieszczanin

10,10′-dibromo-9,9′-bianthracene undergoes efficient Heck coupling with a series of para-substituted styrenes in the presence of a simple palladium-based catalytic system. The reaction proceeds with complete regio- and stereoselectivity. The disadvantage of this method is the minor competitive catalytic hydrodebromination.

This study aimed to create new possibilities in the syntheses of aryl‐arylethynyl‐naphthalene and anthracene derivatives. Starting from simple structures, i.e., ß‐ketoesters, 1,4‐di(aryl, heteroaryl)buta‐1,3‐diynes, and arynes, via 5‐aryl‐4‐(arylethynyl)pyran‐2‐ones, the target structures were successfully obtained by a simple procedure (in a one‐pot or a two‐step version). On the way to the final structures, an innovative and very effective synthetic method for obtaining aryl‐arylethynyl‐pyran‐2‐ones was developed. This unprecedented procedure turned out to be fully regioselective, namely only 5‐aryl‐4‐(arylethynyl)‐3,6‐dimethylpyran‐2‐ones were obtained in the reaction involving ethyl 2‐methyl‐3‐oxobutanoate and 1,4‐diarylbuta‐1,3‐diyne mediated by a Re‐catalyst. It seems that steric effects associated with the Re─C and C─C bond lengths play a decisive role with regard to the regioselectivity. Importantly, the aforementioned procedure is very simple, which makes it completely different from the only previously described procedure dedicated to structurally similar pyranones. Undoubtedly, such substituted 2‐pyranones, naphthalenes, and anthracenes are practically unavailable via any other way, especially via such a simple and convenient synthetic route. All the newly obtained aryl‐arylethynyl‐pyran‐2‐ones and aryl‐arylethynyl‐arenes were fully characterized, including DFT calculations and thermal, optical, and electrochemical properties. The presence of a triple bond in the obtained compounds definitely changes their properties, especially in comparison to structures without a triple bond.

The involvement of 1,3-dipolar cycloaddition (1,3-DP), double bond migration, metathesis, and nitrile oxide (including in situ-generated nitrile oxide) as dipoles, together with the C=C bond containing dipolarophiles, in the syntheses of 2-isoxazolines is presented. Methods for synthesizing isoxazolines (other than 1,3-DP cycloaddition) were also presented briefly. Various methods of nitrile oxide preparation, especially in situ-generated procedures, are presented. Special attention was paid to the application of various combinations of 1,3-DP cycloaddition with double bond migration (DBM) and with alkene metathesis (AM) in the syntheses of trisubstituted isoxazolines. Allyl compounds of the type QCH₂CH=CH₂ (Q = ArO, ArS, Ar, and others) play the role of dipolarophile precursors in the combinations of DPC mentioned, DBM and AM. Mechanistic aspects of cycloadditions, i.e., concerted or stepwise reaction mechanism and their regio- and stereoselectivity are also discussed from experimental and theoretical points of view. Side reactions accompanying cycloaddition, especially nitrile oxide dimerization, are considered. 2-Isoxazoline applications in organic synthesis and their biological activity, broad utility in medicine, agriculture, and other fields were also raised. Some remaining challenges in the field of 1,3-DP cycloaddition in the syntheses of isoxazolines are finally discussed.

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.