Graduate School of Pharmaceutical Sciences, University of Tokyo, Japan

A synthetic chemist takes inspiration from sketching structures.

I enjoy drawing chemical structures of complex natural products and imagining how their polar functional groups, such as –OH and –NH2, interact with biopolymers. I usually first draw a carbon framework of the molecule on paper and then add the required groups. Of course, this order of 'functionalizations' has almost nothing to do with any synthetic scheme I might use for that molecule. Tedious multi-step manipulations are often needed just to introduce one oxygen or nitrogen. Making a molecule will never be as easy as drawing one.

Many research groups are trying to make it easier by devising one-step introductions of complete polar groups into carbon frameworks. One of the latest examples comes from Mark Chen and Christina White (Science, 318, 783–787; 2007). They used a new iron catalyst and hydrogen peroxide to convert specific hydrogens to hydroxyl groups on the carbon skeletons of a variety of molecules.

The catalyst seems to be able to differentiate a site of functionalization from other potentially oxidizable C–H bonds by the balance of two factors: electron-richness and steric accessibility of the bond. Chen and White were able to oxidize the antimalarial natural product (+)-artemisinin at just one predicted position to produce (+)-10-(beta)hydroxyartemisinin. Their work represents a definite advance in the direct functionalization of carbon skeletons.

Every chemist dreams about placing functional groups anywhere they want as easily as drawing them on paper. The direct C–H oxidation reaction should allow us to perform such manipulations and holds great promise for simplifying the synthesis of complex molecules.