Young wine in Mainz and some chemoselectivity lessons

Professor Sigi Waldvogel picked me up from the Frankfurt airport yesterday and we went straight to his lab’s barbeque, which was an awesome way to meet the students and sample some local delicacies, including the delicious federweisser, the likes of which I have never tasted before. This is the so-called “young wine” that can be bought locally and can certainly not be transported very far because it is still brewing. There is no tight cover on the bottle, as you can see – just a bit of foil (otherwise there would be an explosion due to CO2). This stuff, along with beer and sausages, made for a memorable evening.

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Earlier today, I had a great time visiting the University of Mainz. I already blogged about one of Sigi’s great Angewandte papers in the past. He continues to trail blaze in the area of electroorganic synthesis and I hope we will find ways to collaborate, particularly given Sigi’s experience with boron-doped diamond as electrode material. I will post something on that in the future.

I also had a pleasure of meeting Professor Till Opatz, who is running a very innovative program in natural products chemistry. Amongst many interesting vignettes he shared with me was a paper that I completely missed several years ago. I am now glad that I have discovered this work as it serves an important lesson in compound characterization. Below is what I am talking about. The nucleophilic attack at the I(+)-activated alkyne was reported some years ago by Larock and colleagues. These authors postulated the regiochemistry shown in the top box. As it turns out, the reaction outcome is different, which was Till’s discovery. I know for sure that there are people in my lab who will be interested in reading this work. The clarification made by Till’s group goes to show that it is prudent to exercise utmost care in structural assignment and to consider all possible outcomes that fit the data. And how many gold-catalyzed reactions might be revisited, ladies and gentlemen? I don’t know. Just saying.

ttt

http://pubs.acs.org/doi/abs/10.1021/jo3017378

2 thoughts on “Young wine in Mainz and some chemoselectivity lessons

  1. it annoys me when people keep forgetting that regular amides are basic and nucleophilic on carbonyl oxygen, not on nitrogen (because nitrogen lone pair is pretty much part of the amide bond) – the situation changes only if there is a non-nucleophilic base strong enough to bring about amide NH deprotonation (which requires a base like Cs2CO3 or K3PO4 or DBU).

  2. That is correct, yet it is often difficult to assume control over something like this (N vs O reactivity) when various additional parameters are involved. For instance, I would say it is fairly reasonable to expect nitrogen oxidation into an N-Hal species in many of these electrophilic reactions. Then, all of a sudden, mechanism might be different.

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