If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.



Crafty Cobalt Polyborylations

Organic Synthesis: New non-precious-metal catalysts enable unprecedented polyborylation of unactivated C–H bonds in alkylarenes

by Stephen K. Ritter
January 25, 2016 | A version of this story appeared in Volume 94, Issue 4

A set of reactions shows addition of one to three boronate groups to toluene.
New cobalt catalysts enable levels of selective polyborylation that have not been achieved before.

Precious-metal catalysts such as iridium and rhodium are widely used to promote C–H borylation reactions, in which a boronate group is installed in place of a hydrogen atom. The aryl boronate product is a useful intermediate that can in turn be used in cross-coupling and other reactions to complete functionalization of the C–H bond. Although functionalizing aryl ring carbons with groups such as boron pinacolate is well-known, less common is achieving addition of the boronate to benzylic carbons in molecules such as toluene. W. Neil Palmer, Paul J. Chirik, and colleagues of Princeton University have now devised a method for adding not just one boronate group to toluene’s methyl group but an unprecedented two or three, depending on the ratio of reactants, amount of catalyst, and reaction time. In addition, their approach works on branched alkylarenes, which has not been accomplished before (J. Am. Chem. Soc. 2015, DOI: 10.1021/jacs.5b12249). The chemistry is made possible by new α-diimine cobalt dialkyl and bis(carboxylate) catalysts the Princeton team has created.


This article has been sent to the following recipient:

Chemistry matters. Join us to get the news you need.