Regioselective Base‐Induced Intramolecular Synthesis of Novel Pyrimido[1,6‐ a ]Selenopheno[3,2‐ d ]Pyrimidines

In this study, we present an efficient and regioselective synthetic approach for the preparation of novel pyrimido[1,6‐ a ]selenopheno[3,2‐ d ]pyrimidine derivatives. The sequence involves the initial condensation of 3‐amino‐2,4‐dicyano‐5‐(pyrrolidin‐1‐yl)selenophene (1) with 5‐bromo‐2,4‐dichloro‐6‐methylpyrimidine (2) , followed by nucleophilic substitution with selected secondary amines. Subsequently, a base‐induced intramolecular cyclization occurring on the nitrile group using NaNH 2 afforded the fused products (6a–f) . Although only a limited number of derivatives were obtained, this sequence offers a straightforward and modular route to fused heterocyclic systems. The structural features, including the disappearance of one nitrile group and the formation of the fused ring system, were characterized by FT‐IR, 1 H NMR, 13 C NMR, HMBC, and 2D NOESY analyses. The obtained data were consistent with the proposed structures and supported the formation of the fused pyrimidine–selenophene framework. This catalyst‐free and operationally simple procedure highlights a practical synthetic pathway to selenium‐containing fused pyrimidines, which have been previously difficult to access. Furthermore, preliminary antibacterial evaluation indicates promising biological potential for the obtained compounds.