Chemists like to coin new terms, which is particularly meaningful when there is a connection to the place of discovery of a given molecule or process. Graduate students are usually well aware of munchnones. These intriguing intermediates are named after Munich, where Professor Huisgen spent a good portion of his career and where he coined the term. Comparatively less known are sydnones, which differ from munchnones by the presence of nitrogen. As a matter of fact, sydnones predate munchnones. They were developed in Sydney by Earl and Mackney back in 1935. Below is an awesome paper by Harrity and co-workers I came across. It showcases the use of sydnones in heterocyclic synthesis.
While the paper is hardly new, I marvel at this way of introducing boron atoms into heterocycles. Cycloaddition/retro-cycloaddition does the trick here. By the way, there is a great review by Mike Willis that contains a lot of other, equally intriguing, cases that employ retro-cycloadditions. Here is a link to Mike’s review: