Generation and regioselective trapping of a 3,4-piperidyne for the synthesis of functionalized heterocycles.

We report the generation of the first 3,4-piperidyne and its use as a building block for the synthesis of annulated piperidines. Experimental and computational studies of this intermediate are disclosed, along with comparisons to the well-known 3,4-pyridyne. The distortion/interaction model is used to explain the observed regioselectivities.