Synthesis of BenzocSelenophenes and Their Analogues: Methods and Advances

ABSTRACT The fusion of benzene with selenophene motifs in hybrid configurations yields two distinct structural types: condensed benzobselenophenes and benzocselenophenes. Benzo c selenophenes are distinguished by the placement of a selenium atom at the second position rather than the first. To date, no specific studies have focused exclusively on this scaffold, which has been predominantly utilized as a versatile building block in various applications. The synthesis of benzo c selenophenes and their analogues can be accomplished through multiple chemical pathways, including (i) selenation reactions using reagents like Woollins' reagent, Na 2 Se 2 /DMSO, 1,1,1,3,3,3‐hexabutyldistannaselenane in toluene, selenium/NMP, and Na 2 Se in THF; (ii) Suzuki, Stille, and Sonogashira coupling reactions; (iii) photocyclization reactions; (iv) nucleophilic and metallic substitution reactions; (v) 2 + 2 + n cycloaddition reactions; and (vi) organometallic reactions, among other methods.