Synthesis and Reactivity of 5‐Bromopenta‐2,4‐diynenitrile (BrC5N): an Access to π‐Conjugated Scaffolds

The synthesis of 5‐bromopenta‐2,4‐diynenitrile (BrC₅N) in three steps from commercially available compounds is reported. Reacting 5‐bromopenta‐2,4‐diynenitrile with secondary amines led to the formation of stable butadiynamines or enynenitriles, depending on the nature of the amine reactant. The reaction of 5‐bromopenta‐2,4‐diynenitrile with simple terminal alkynes in the presence of secondary amines, copper, and palladium catalysts, provided a straightforward access to original polyfunctional carbon‐rich scaffolds. In this work, different alkynes and secondary amines were tested, which allowed for the preparation of a family of substituted dienes. Given the high synthetic potential of 5‐bromopenta‐2,4‐diynenitrile, we also prepared iodinated counterparts of this compound, that is, 5‐iodopenta‐2,4‐diynenitrile and its lower homologue 3‐iodopropiolonitrile. The UV‐visible spectrum of some relevant compounds was also recorded.