Organic chemistry: Precision pruning of molecules.

Abstract

If organic molecules were trees, then the numerous carbon–hydrogen bonds within them would be leaves. A catalyst that targets one 'leaf' out of many similar other ones looks set to be a huge leap for synthetic chemistry. See Letter p.230 Organic synthesis has traditionally relied heavily on the introduction and manipulation of functional groups, such as carbon–oxygen or carbon–halogen bonds. Much current research is focused on a potentially powerful alternative strategy in which carbon–hydrogen bonds, normally much less reactive and therefore resistant to functionalization, are somehow persuaded to be more easily modified. These authors report that it is possible to selectively functionalize an unactivated C–H bond by the use of well-defined catalysts to control the site selectivity, without the need for a directing or anchoring group present in the molecule. They use dirhodium catalysts to achieve diastereoselective and enantioselective C–H functionalization of n-alkanes and terminally substituted n-alkyl compounds. The reactions proceed in high yield and can be carried out on substrates containing other functional groups such as halides, silanes, and esters.