Computational Insights into Intramolecular Cross-Coupling of Quaternary Borate Salts

17 February 2021, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

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.

Keywords

C-C coupling
Cross-coupling
Reaction mechanisms
Computational Chemistry
Organoborates
Electrochemistry

Supplementary materials

Title
Description
Actions
Title
Computational insights borate salts SI-values
Description
Actions
Title
Computational insights borate salts SI-geometries
Description
Actions

Comments

Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.