Issue 13, 2021

Catalytic and non-catalytic hydroboration of carbonyls: quantum-chemical studies

Abstract

The addition of hydroboranes across several unsaturated moieties is a universal synthetic tool for the reduction or functionalization of unsaturated moieties. Given the sustainable nature of this process, the development of more environmentally-benign approaches (main-group catalysis or uncatalysed approaches) for hydroboration has gained considerable recent momentum. The present paper examines both catalyst-free and KF-mediated hydroboration of carbonyl compounds with the use of quantum-chemical methods. The results of computations for several potential reaction pathways are juxtaposed with experiment-based calculations, which leads to stepwise mechanisms and energy profiles for the reactions of pinacolborane with benzaldehyde and acetophenone (in the presence of KF). For each step of these reactions, we provide an accurate description of the geometric and electronic structures of corresponding stationary points. Five different levels of theory are employed to select the most applicable theoretical approach and develop a computational protocol for further research. Upon selection of the best-performing methods, larger molecular systems are studied to explore possible more complex pathways at the M06-2X/6-311++G(2d,p) and ωB97XD/6-311++G(2d,p) levels of theory, which brings up multi-pathway, overlapping catalytic cycles. The mechanism of solvent-free, catalyst-free hydroboration of aldehydes is also revisited through the prism of the elaborated methodology, which leads to a whole new perspective on the pathways of this and similar reactions, with a multimolecular cascade of hydride transfers being more energetically favoured than a four-membered transition state.

Graphical abstract: Catalytic and non-catalytic hydroboration of carbonyls: quantum-chemical studies

Supplementary files

Article information

Article type
Paper
Submitted
07 yan 2021
Accepted
11 mar 2021
First published
11 mar 2021

Org. Biomol. Chem., 2021,19, 3004-3015

Catalytic and non-catalytic hydroboration of carbonyls: quantum-chemical studies

M. Nowicki, K. Kuciński, G. Hreczycho and M. Hoffmann, Org. Biomol. Chem., 2021, 19, 3004 DOI: 10.1039/D1OB00037C

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements