Unexpected Synthesis of a 5H-chromeno[3,4-c]pyridine Derivative from 4-Chlorocoumarin-3-carbaldehyde and Malononitrile

In the reaction of 4‐chlorocoumarin‐3‐carbaldehyde with malononitrile in the presence of piperidine, a piperidinium salt of a novel tricyclic chromeno[3,4‐c]pyridine derivative was isolated instead of the expected “tert‐amino effect” product. When hexamethyleneimine (azepane) was used as a base, the corresponding azepanium salt (same anion) was obtained. Both structures have been formulated on the basis of their spectral (IR, NMR, MS) behavior and elemental analyses. In addition, the structure of the piperidinium salt was confirmed by means of X‐ray crystallographic analysis.