2-Selenochromenes and their salts: Structure and reactivity

The fusion of benzene with 4H-selenopyran motifs yields three distinct structures: condensed 2H-selenochromene, 4H-selenochromene, and 1H-isoselenochromene. Notably, isoselenochromene features a selenium atom in the second position rather than the first, a configuration that, as far as current knowledge indicates, lacks specific published reports and has predominantly served as a foundational building block. The synthesis of 1H-isoselenochromenes and their analogues can be achieved through various chemical pathways, such as the Sonogashira coupling reaction, nucleophilic addition, organometallic reactions, metal substitution, and other established methods in organic synthesis.