(Invited) Stereoselective Synthesis of Molecular Nanographenes

Abstract

The precise control of stereogenic elements in chemical structures has always been a higly demanding synthetic task.1 In this regard, most of the currently available asymmetric methods require the presence of a heteroatom in the starting substrates that serves as an anchoring point for the successful transfer of chiral information. This eventually emerges, typically, in the form of a new stereogenic centre while the heteroatom remains in the product. This general procedure could account for the lack of stereoselective protocols in all-carbon atom compounds.2,3 Actually, optically active nanographenes have so far been obtained only by either top-down or bottom-up racemic syntheses, followed by time consuming chiral chromatographic separations.4-6 In this presentation, we will introduce a general overview on the efforts carried out in our group in the search for stereoselectivity to introduce and extend stereogenic elements into polyaromatic sp2 carbon-based molecular nanographenes. Acknowledgements The author acknowledge support from the MICIN of Spain (project: PID2020-114653RB-I00) and the European Research Council (ERC) Synergy Grant “TOMATTO” (Project 951224). References H. Kuang, C. Xu, Z. Tang, “Emerging Chiral Materials”, Adv. Mater. 2020, 32, e2005110.M. Rickhaus, M. Mayor, M. Juricek, “Strain-induced helical chirality in polyaromatic systems”, Chem. Soc. Rev. 2016, 45, 1542-1556.J. M. Fernández-García, P. Izquierdo-Garcia, M. Buendia, S. Filippone, N. Martín, “Synthetic chiral molecular nanographenes: the key figure of the racemization barrier”, Chem. Commun. 2022, 58, 2634-2645.P. J. Evans, J. Ouyang, L. Favereau, J. Crassous, I. Fernández, J. Perles-Hernáez, N. Martín "Synthesis of a Helical Bilayer Nanographene" Angew. Chem. Int. Ed. 2018, 57, 6774 –6779.P. Izquierdo-García, J. M. Fernández-García, I. Fernández, J. Perles, N. Martín, “Helically Arranged Chiral Molecular Nanographenes", J. Am. Chem. Soc., 2021, 143, 11864−11870.M. Vázquez-Nakagawa, L. Rodríguez-Pérez, N. Martín, M. A. Herránz, “Supramolecular Assembly of Edge Functionalized Top-Down Chiral Graphene Quantum Dots”, Angew. Chem. Int. Ed. 2022, 61, e202211365.