Issue 8, 2014

A simple and practical catalytic electron transfer system composed of TiCl4 and metallic Yb: application in carbonyl olefination and insight into the mechanism

Abstract

The McMurry-type olefinations have become a powerful tool in organic synthesis. However, the use of stoichiometric amounts of unmanageable Ti species and the generation of a large amount of salts limit their applications on the industrial scale. This paper outlines a simple and practical catalytic electron transfer (ET) system composed of TiCl4 and Yb, which turned out to be effective for homo- and cross-deoxygenative coupling of aldehydes and ketones. Specifically, the method is based upon the strategy that the low valent Ti species abstracts oxygen from carbonyl and delivers them to highly oxophilic Yb in an unprecedented manner. Remarkably, the present process is operationally simple, minimizes the generation of chemical waste, and makes the only by-product Yb2O3 as a solid easily removed and utilized; furthermore, the yield improved significantly of that obtained in the stoichiometric version in our system. Our mechanistic data not only provide the direct evidence that Ti(IV) can facilitate the part deoxygenation of pinacol at room temperature, but also demonstrate, for the first time, that for bulky ketones the turnover-limiting step is the Ti-mediated carbonyl coupling rather than the subsequent deoxygenation of the resulting pinacolate intermediates, which are different from the previous observations.

Graphical abstract: A simple and practical catalytic electron transfer system composed of TiCl4 and metallic Yb: application in carbonyl olefination and insight into the mechanism

Supplementary files

Article information

Article type
Research Article
Submitted
14 May 2014
Accepted
14 Jul 2014
First published
15 Jul 2014

Org. Chem. Front., 2014,1, 929-935

Author version available

A simple and practical catalytic electron transfer system composed of TiCl4 and metallic Yb: application in carbonyl olefination and insight into the mechanism

L. Zhang, X. Yu, L. Zhang, X. Zhou and Y. Lin, Org. Chem. Front., 2014, 1, 929 DOI: 10.1039/C4QO00140K

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