K+ -Mediated vs Pd-Catalyzed Cyclotrimerization of 9,10-Didehydrotribenzo[8]annulene (TribenzoCOTyne): Stereodivergent Access to (α,α,α)- and (α,α,β)-Fragments of Cubic Graphite

Bello García, JesúsVarela Carrete, Jesús ÁngelSaá Rodríguez, Carlos2024-12-202024-12-202024Bello-García, J., Varela, J. A., Saá, C. (2024). K+‐Mediated vs Pd‐Catalyzed Cyclotrimerization of 9,10‐Didehydrotribenzo[8]annulene (TribenzoCOTyne): Stereodivergent Access to (α,α,α)‐ and (α,α,β)‐Fragments of Cubic Graphite. "Angewandte Chemie International Edition", vol. 63, e2024140171433-7851https://hdl.handle.net/10347/38245A remarkable stereodivergent cyclotrimeriza-tion of 9,10-didehydrotribenzo[8]annulene (tribenzoCO-Tyne) to the corresponding (α,α,α)- and (α,α,β)-benzo-fused derivatives has been developed by controlling the reaction conditions. While the K+ -mediated cyclotrime-rization afforded the (α,α,α) stereoisomer, using Pd as a catalyst resulted in the (α,α,β)-derivative. Both stereo-isomers were evidenced by spectroscopic data and crystal X-Ray analysis. The (α,α,α) stereoisomer is a fragment of cubic graphite (CG), an elusive 3D carbon allotrope that contains carbon cages, since all of its sixty carbons are part of the structure of CG, and 36 constitute a part of the C48 molecular cage of CG. Experimental and computational mechanistic studies revealed that the potassium ion would play a key role as a template to favor the formation of the (α,α,α) stereo-isomeeng© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbHAttribution-NonCommercial-NoDerivatives 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/Benzo[8]annulenesCOT conformersCOTynes (didehydro[8]annulenesCubic graphiteCyclotrimerizations2306 Química orgánicaK+ -Mediated vs Pd-Catalyzed Cyclotrimerization of 9,10-Didehydrotribenzo[8]annulene (TribenzoCOTyne): Stereodivergent Access to (α,α,α)- and (α,α,β)-Fragments of Cubic Graphitejournal article10.1002/anie.2024140171521-3773open access