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Computational Insights into Intramolecular Cross-Coupling of Quaternary Borate Salts
preprintsubmitted on 16.02.2021, 08:42 and posted on 17.02.2021, 05:04 by Florian Matz, Arif Music, Dorian Didier, Thomas C. Jagau
Cross-coupling reactions for C-C bond formation represent a cornerstone of organic synthesis. In most cases, they make use of transition metals, which has several downsides. Recently, metal-free alternatives relying on electrochemistry have gained interest. One example of such a reaction is the oxidation of tetraorganoborate salts that initiates aryl-aryl and aryl-alkenyl couplings with promising selectivities. This work investigates the mechanism of this reaction computationally using density functional and coupled-cluster theory. Our calculations reveal a distinct difference between aryl-alkenyl and aryl-aryl couplings: While C-C bond formation occurs irreversibly and without an energy barrier if an alkenyl residue is involved, many intermediates can be identified in aryl-aryl couplings. In the latter case, intramolecular transitions between reaction paths leading to different products are possible. Based on the energy differences between these intermediates, we develop a kinetic model to estimate product distributions for aryl-aryl couplings.
Theoretical Chemistry of Unbound Electrons
European Research CouncilFind out more...
DFG grant 2227/2-1
Fonds der Chemischen Industrie
SFB 749: Dynamics and Intermediates of Molecular Transformations
Deutsche ForschungsgemeinschaftFind out more...