Monday, November 27, 2017

New catalyst controls activation of a carbon-hydrogen bond

Chemists have developed another catalyst that can selectively activate a carbon-hydrogen bond, part of an ongoing strategy to revolutionize the field of organic synthesis and open up new chemical space. The journal Nature is publishing the work by chemists at Emory University, following on their development of a similar catalyst last year. Both of the catalysts are able to selectively functionalize the unreactive carbon-hydrogen (C-H) bonds of an alkane without using a directing group, while also maintaining virtually full control of site selectivity and the three-dimensional shape of the molecules produced.

"Alkanes have a lot of C-H bonds and we showed last year that we can bring in one of our catalysts and pluck out a particular one of these bonds and make it reactive," says Huw Davies, an Emory professor of organic chemistry whose lab led the research. "Now we are reporting a second catalyst that can do the same thing with another C-H bond. We're building up the toolbox, and we've got more catalysts in the pipeline that will continue to expand the toolbox for this new way of doing chemistry."
The Davies lab is developing a suite of dirhodium catalysts that bypass the need for a directing group to control the C-H functionalization. The dirhodium catalysts are encased within a three-dimensional scaffold.

"The dirhodium is the engine that makes the chemistry work," Davies says. "The shape of the scaffold around the dirhodium is what controls which C-H bond the catalyst works on." 


Kuangbiao Liao, Thomas C. Pickel, Vyacheslav Boyarskikh, John Bacsa, Djamaladdin G. Musaev, Huw M. L. Davies. Site-selective and stereoselective functionalization of non-activated tertiary C–H bonds. Nature, 2017; DOI: 10.1038/nature24641 

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