Facile synthesis and functionalization of fluoranthenes via intramolecular [4+2] annulations between thiophenes and alkynes

Fluoranthenes have attracted tremendous attention due to their unique optoelectronic properties and ex-tensive applications. Although several synthetic methodologies have been developed for the preparation of fluoranthene derivatives, it is still unfavorable to functionalize the fluoranthene framework at different positions due to the relatively low selectivity and reactivity. Herein, a catalyst-free intramolecular [4 + 2] annulation between thiophenes and alkynes is developed towards the synthesis of fluoranthenes. Alto-gether 20 examples have been demonstrated using this method. Various functional groups can be pre-cisely introduced into the fluoranthene skeleton at different positions by simply tuning the substituents on the thiophenes and alkynes. The conjugation of the fluoranthene can be facilely extended through different directions. Furthermore, the feasibility of this [4 + 2] annulation reaction is also investigated by density functional theory calculations. Therefore, this protocol provides not only a synthetic methodol-ogy towards fluoranthenes with substituents functionalized at different positions, but also an effective pathway to construct large polycyclic aromatic hydrocarbons containing fluoranthene moieties. (c) 2023 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.

Automated summary

A catalyst-free intramolecular [4 + 2] annulation reaction has been developed for the synthesis of fluoranthenes with functionalized substituents at different positions. By tuning the substituents on thiophenes and alkynes, various functional groups can be precisely introduced into the fluoranthene framework, and the conjugation can be easily extended. Density functional theory calculations confirm the feasibility of this reaction. Therefore, this method provides a synthetic methodology for fluoranthenes and a pathway for constructing polycyclic aromatic hydrocarbons containing fluoranthene moieties.