I am in Brasilia, the capital of Brazil, where I am attending the 6th International Conference on Multicomponent Reactions (http://www.mcr2015.unb.br). I have learned a lot of interesting things today and, while I could discuss something that is “hot off the press”, I am going to instead comment on something that is old, yet not well known.
Take a look at the triazole synthesis shown above. I learned about this reaction from the talk of Professor Bernie Westermann, who shared with us his latest results in the area of biological probe design. This 1986 route to triazoles reported by Sakai is not particularly high-yielding, yet it allows me to relate to a discussion I had with my graduate students several weeks ago. Here is the irony: once some reactions reach a certain level of stardom, they lose their educational value. I refer to azide-alkyne cycloaddition, olefin metathesis, Suzuki reaction, etc. Whenever we have a group meeting where my students try to work on a synthetic problem set, I try to emphatically prohibit them from doing the obvious. In other words, if you see a cyclic alkene – do not make it using metathesis, if you see a triazole – forget that azides exist, and so on. Think about something else.
The example above has been chosen to emphasize that there are alternative ways of looking at the stomping grounds of contemporary synthesis. As a corollary to that, I suppose that it is possible for a reaction to fall victim to its own success. This is the way I see it, at least when it comes to advanced chemistry education when we expect our students to display original thinking. Sakai’s case is also curious as it provides a product with a chain of four nitrogen atoms. It is not clear what to do with the N-Ts “overhang”, but I think this chemistry is really nice.