Friday, June 15, 2012

Adventures in Publication: Malaria Sandwich

Hot on the heels of the recent ferrocene-based carbonic anhydrase inhibitors (see Pipeline or Chemistry Blog for more perspective) comes a few more medicinally-inclined sandwich compounds. Published in back to back ASAPs, the new leads stitch together an antimalarial quinoline and a glycoside with some ferrocenyl 'Scotch tape.' The resulting "novel trifunctional conjugates" purport to treat chloroquine-resistant P. falciparum strains with low-micromolar potency.

Chirality? At that carbon?
A few salient questions: First, if these compounds represent med-chem advances, why are they in Organometallics, of all places? Surely this wasn't the first Editor's desk they landed upon! Second, both papers seem to be variations on a theme, so why not just combine them and make one stronger paper? Lastly, can anyone interpret the stereochemistry shown in this intermediate? It's drawn to suggest a chiral acetal; my o-chem 'spider sense' says that cannot be. 

To my med-chem inclined readers: what do you make of these molecules? Bandwagon hype, or real advance?

Update, 6/15/12 - Changed figure caption, and "ketal" to "acetal"


  1. Well, they are attached to mefloquine in the papers AFAIK, so it seems like they just use the Fe complex to fool the P. falciparum to transport it into the cell. Not sure how they propose the action, and I can't read anything but the abstract, but... probably BH instead of RA.

  2. ChemDraw is notoriously bad at drawing organometallic complexes, especially sandwich complexes. Perhaps they were trying to artistically show the connectivity of the acetal group by using the wedge bond. This is not standard practice, in my experience. The use of the standard bond suffices (as they have done in the lower Cp ring.)

    You're correct- that carbon is sp2, so the connectivity to the Cp ring is in the plane of the ring.

  3. Your o-chem 'spider sense' is sharp. The acetal sp3 carbon is not chiral because two of its bonds are to the same thing and thus all mirror planes are super imposable. So, no, there shouldn't be any stereochemistry shown in the figure.