On-Surface Site-Selective Cyclization of Corrole Radicals.
Radical cyclization is among the most powerful and versatile reactions for constructing mono- and polycyclic systems, but has, to date, remained unexplored in the context of on-surface synthesis. We report the controlled on-surface synthesis of stable corrole radicals on Ag(111) via site-specific dehydrogenation of a pyrrole N-H bond in the 5,10,15-tris(pentafluoro-phenyl)-corrole triggered by annealing at 330 K under ultrahigh-vacuum conditions. We reveal a thermally induced regioselective cyclization reaction mediated by a radical cascade and resolve the reaction mechanism of the pertaining cyclodefluorination reaction at the single-molecule level. Via intramolecularly resolved probing of the radical-related Kondo signature, we achieve real space visualization of the distribution of the unpaired electron density over specific sites within the corrole radical. Annealing to 550 K initiates intermolecular coupling reactions, producing an extended π-conjugated corrole system.
['Tebi|Stefano|S|', 'Paszkiewicz|Mateusz|M|', 'Aldahhak|Hazem|H|', 'Allegretti|Francesco|F|', 'Gonglach|Sabrina|S|', 'Haas|Michael|M|', 'Waser|Mario|M|0000-0002-8421-8642', 'Deimel|Peter S|PS|', 'Aguilar|Pablo Casado|PC|', 'Zhang|Yi-Qi|YQ|', 'Papageorgiou|Anthoula C|AC|0000-0003-1054-0097', 'Duncan|David A|DA|', 'Barth|Johannes V|JV|', 'Schmidt|Wolf G|WG|', 'Koch|Reinhold|R|', 'Gerstmann|Uwe|U|', 'Rauls|Eva|E|', 'Klappenberger|Florian|F|0000-0002-2877-6105', 'Schöfberger|Wolfgang|W|0000-0002-8055-8906', 'Müllegger|Stefan|S|']
cyclization corrole regioselectivity defluorination network radical cascade reactions surface