There were many great talks yesterday at the Belgian Organic Synthesis Symposium, but as I have time to describe just one, I’ll mention Eric Jacobsen’s tour de force about hydrogen-bonding catalysis. This seems to be an area that’s really kicking off right now.
His thesis is that hydrogen-bonding catalysts shouldn’t be thought of in the way that chemists tend to conceptualize asymmetric catalysts in general – that is, as molecules or complexes that bind to substrates in order to block the approach of reactants from certain directions. Instead, he made the case that hydrogen-bonding catalysts act more like enzymes, activating and/or stabilizing the substrate (or the substrate’s transition state)through hydrogen bonding. That’s not to say that steric interactions are unimportant, clearly they still have an impact. But to fully understand how hydrogen-bonding catalysts work, he argues that you need to look first at the stabilizing effects of non-covalent interactions.
He backed this up with many case studies of hydrogen-bonding catalysts from his own lab (such as those for Claisen rearrangements, polyene cyclizations and Strecker-like reactions), in each case providing a detailed analysis of how each catalyst works. It’s all beautiful stuff, and you find some it in JACS (see the abstract for his analysis of the Strecker reaction here).
Today is the last day of the meeting, so this is where I’ll sign off from Belgium. I’ve only been able to discuss a handful of the presentations, but there were many other highlights at this meeting. I can only encourage organic chemists out there to come to the next meeting in the BOSS series, in 2012 – you won’t be disappointed.
Andrew Mitchinson (Senior Editor, Nature)