Happy New Year, everyone! Lets kick 2017 by looking at what is up with dyotropic rearrangements. I mentioned them in the past, but still have trouble finding too many of these fascinating reactions in papers. Perhaps one of the reasons for this lack of occurrence is that substrates for dyotropic processes tend to be fairly complex. This naturally brings me to total synthesis, where the starting material complexity is a moot point. The example below comes from the lab of Professor Thomas Magauer. I met him last summer in Munich and became acquainted with his innovative program. Now that his paper dedicated to the synthesis of dictooxetane is out, you can also enjoy the rare case of a dyotropic process that has been put to good use here. In this case, an epoxide/oxetane system participates in a dyotropic rearrangement. As a result of the bond switch, the scaffold gets transformed into a tetrahydrofuran/oxetane, which represents a downhill process. Copper tetrafluoroborate was used as the Lewis acid to trigger this process.
amphoteros 
thank you! very interesting reaction to learn about. one thing though: although it is highlighted by a dyotropic reaction, the natural product is actually called dictyoxetane (not dyctooxetane )
Oh yes, thanks.
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After checking SI of the paper, my ave of this reaction somewhat diminished, but my respect to the first author skyrocketed 🙂
You bet!
Thanks for the kind comment, Slava.
I coincidentally found this post and thought I’d give you a personal response:
You’re absolutely right, the attractiveness of the whole transformation is somewhat diminished by formation of the two by-products. We were pretty excited by the discovery of this dyotropic rearrangement and quite frankly did not extensively optimize the reaction any further. As you might have noted, we used the hydrate of copper tetrafluoroborate, which accounts for the by-product resulting from opening of the epoxide with water (37%, compound 42 in the SI). Using the non-hydrated form of the Lewis acid would presumably avoid formation of this compound… Thus, I strongly believe the yield of the dyotropic rearrangement product could well be improved by more extensive reaction optimization.
If you’re further interested in reading about a few fascinating dyotropic rearrangements in the field of natural product synthesis, you might enjoy the following, recent highlight article:
http://pubs.rsc.org/en/content/articlelanding/2017/np/c7np00005g#!divAbstract
Thanks for the feature on “Amphoteros”, I always enjoy reading these blog posts!
wow, thanks for the detailed response; keep the good stuff coming 🙂