Shifting cyclopropane rings around

I do not have a habit of reading or commenting on biosynthesis papers, but there is often a lot to learn in them, particularly when cationic rearrangements are involved. Dean Tantillo showed us some fascinating examples several weeks ago, so I started paying more attention to terpene chemistry. Below is a real piece of razzle-dazzle, exemplified by a reaction that rearranges the skeleton of an 8-membered terpenoid system of cyclooctatin. The colored circles represent labels (one is carbon- and the other one is deuterium-based). One sees such “swaps” quite rarely, particularly in biosynthesis. The unique carbon–carbon bond rearrangement shown below is thought to involve cyclopropane intermediates. As is often the case in studies such as this, the authors resorted to labeling experiments and obtained their precursors from 13C-labeled glucose (cell culture work) in combination with in vitro reactions of regiospecifically deuterated geranylgeranyl substrates. The overall process is catalyzed by cyclooctat-9-en-7-ol synthase in a stereospecific fashion. I do find the water attack (depicted by the authors) somewhat of a bold statement from a synthetic organic chemist’s point of view…

OK, so this is a fairly esoteric example and you might wonder why I am bringing this up. I suppose it is because I find it interesting to look at stuff that is unusual and lies outside the beaten track. I have always loved such science and I always will.


2 thoughts on “Shifting cyclopropane rings around

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