Monday, July 7, 2014

A Cage-y Déjà Vu

I love finding molecular "diamonds in the rough." Especially when they look, well, a bit like diamonds.

While strolling through the literature, I did a double-take at this polycyclic caged structure reported by Santiago Vázquez  (Universitat de Barcelonaand coworkers. Wow!

Source: ACIEE 2014, Vasquez et. al.

Spawned from a "highly pyramidalized" (nonplanar) olefin dimerization, it features three cyclobutanes, four "envelope" cyclopentanes, and four cyclohexanes locked in their "boat" conformations (Even worse? All those eclipsing methyl groups on each end . . .jeepers). One might expect a thing like that to fall apart in a minute with a little heat, but, amazingly, the compound remains stable up to 500 degrees Celsius.

Model of the "highly-pyramidalized" olefin monomer.
Phil Baran used to say that you could judge the strain based
on how badly your model's bonds bent...

A little reference digging proved that similar caged olefins were first produced almost half a century ago at Smith Kline & French, using a seven-step prep reliant on chloroketals and long-duration sulfuric acid stirs (yuck). A major step forward came in 1970, when Avila and Silva (San Fernando Valley State U) realized that blasting UV light at a double-Diels Alder adduct of acetylene dicarboxylic acid led to a symmetric anhydride precursor.

Vázquez extended this little gem of a starting material towards finding active antiviral analogues of amantadine. Using the imide version of Silva's anhydride, Vázquez produced a caged secondary amine (see right) that exhibits activity against mutant versions of the H1N1 flu virus. His compound also inhibits the influenza A wild-type proton channel; molecular dynamics simulations indicate that it performs a "flip" relative to bound amantadine that plugs up this pore more effectively.

Let's just hope that these new polycycles get an easier-to-pronounce nickname. 

Octopane? Rocketane? Congestane? I'm open to suggestions!


  1. Reminds me of these sentinel things in "the matrix". There's something about these four methyl groups sticking out like tentacles in the back.

  2. Interestingly enough, I expect there to be only 3 proton signals in this molecule. I work with somewhat similar structures (polycyclics) and that kind of degeneracy from high symmetry is common. At times it can be hard to see what you're looking at, but when a reacton goes wrong, often times you lose symmetry which is very visible. All in all, I think it's a good thing because it's a case of a relatively large molecule that doesn't have a messy spectrum.