The right place at the right time

I am in Ottawa at the moment, attending the 2016 CHRP (Collaborative Health Research Projects) grant review panel. I wish all of the grants I had to read would get funded! The level of science is quite high. Now is our coffee break, so I have some time…

Today is a second post in a row where I mention some kind of azide chemistry. That’s ok because, as someone who has been interested in aziridine chemistry for a while, I can’t let the recent Angewandte paper by Shen and colleagues from Changzhou go without due notice. Below you see a graphical summary. While there is nothing new in intramolecular Diels-Alder reactions, it is always good to see cases in which a particularly unstable dienophile is created. In the present case, the authors show how vinyl azides undergo thermal transformation into azirines, which are then positioned at the right place and time to undergo [4+2] cycloaddition. Good luck making the resulting tricycles by any other means! I think the “latent azirine concept” is quite neat and should find many applications in alkaloid synthesis, among other things. Someone should come up with a quantifiable metric for how rapid complexity increases in a single transformation (maybe it already exists, but I just can’t think of it at the moment). The Shen paper is really impressive in this regard, although (there is always this “although”…) one has to make some fairly obscure starting materials.