Synthesis, Stereochemical and Photophysical Properties of Functionalized Thiahelicenes

Year: 2022

Authors: Pelliccioli V., Cardano F., Renno G., Vasile F., Graiff C., Mazzeo G., Fin A., Longhi G., Abbate S., Rosetti A., Villani C., Viscardi G., Licandro E., Cauteruccio S.

Autors Affiliation: Univ Milan, Dipartimento Chim, Via Golgi 19, I-20133 Milan, Italy; Georg August Univ Gottingen, Inst Organ & Biomol Chem, Tammannstr 2, D-37073 Gottingen, Germany; Univ Torino, Dipartimento Chim, Via P Giuria 7, I-10125 Turin, Italy; Univ Parma, Dipartimento Sci Chim Vita & Sostenibilita Ambien, Parco Area Sci 17-A, I-43124 Parma, Italy; Univ Brescia, Dipartimento Med Mol & Traslaz, Viale Europa 11, I-25123 Brescia, Italy; Univ Turin, Dept Drug Sci & Technol, Via P Giuria 9, I-10125 Turin, Italy; CNR, CSMT, Res Unit Brescia, Ist Nazl Ott INO, VIA Branze 45, I-25123 Brescia, Italy; Sapienza Univ Roma, Dipartimento Chim & Tecnol Farmaco, Ple A Moro 5, I-00185 Rome, Italy.

Abstract: We report on the synthesis of a novel class of functionalized thia[6]helicenes and a thia[5]helicene, containing a benzothiophene unit and a second heteroatom embedded in the helix (i.e., nitrogen and oxygen) or a pyrene or a spirobifluorene moiety. These systems are obtained through straightforward and general procedures that involve: (i) palladium-catalyzed annulation of iodo-atropoisomers with internal alkynes and (ii) Suzuki coupling of iodo-atropoisomers with phenyl boronic acid followed by a Mallory-type reaction. Both experimental and theoretical studies on the configurational stability of some selected thia[6]helicenes confirmed their stability toward racemization at room temperature, while the pyrene-based thia[5]helicene was found to be unstable. Moreover, the configuration assignment for one representative thiahelicene was established through the comparison between experimental and theoretical circular dichroism (CD) spectra. A systematic study of the photophysical properties of both thiahelicenes and the corresponding atropoisomers has been carried out to provide a complete overview on the new molecules proposed in this work. The obtained data showed regular trends in all the thiahelicene series with spectroscopic traits in line with those previously observed for similar heterohelicenes.

Journal/Review: CATALYSTS

Volume: 12 (4)      Pages from: 366-1  to: 366-18

More Information: S.C. thanks Universita degli Studi di Milano for the financial support (Piano di Sostegno alla Ricerca 2015/2017-Linea 2, Azione A-Giovani Ricercatori). S.A. and G.L. thank Support from the Italian MIUR (PRIN 2017, project Physico-chemical Heuristic Approaches: Nanoscale Theory of Molecular Spectroscopy (PHANTOMS), prot. 2017A4XRCA).
KeyWords: thiahelicenes; synthetic methodology; palladium catalysts; annulation reactions; HPLC; circular dichroism; DFT calculations
DOI: 10.3390/catal12040366

Citations: 4
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