Selenium-containing heterocycles have emerged as versatile frameworks with promising applications in medicinal chemistry due to their unique physicochemical properties and biological activities. This abstract consolidates our recent advanced methodologies for synthesizing selenium-enriched fused heterocycles, focusing on selenophene and selenazoles. The first approach highlights the synthesis of selenopheno[2,3-e][1,2,4]triazolo[1,5-c]pyrimidines via Dimroth rearrangement, starting from hydrazinyl-selenopheno precursors. This multistep protocol employs electrophilic carbons (orthoesters and carbon disulfide) followed by S-alkylation to produce highly functionalized tricyclic compounds. [1] The other approach investigates the antioxidant properties of selenium-fused chalcogenophenes, specifically selenopheno[3,2-d]pyrimidines. Employing a base-promoted cascade cyclization of 3-amino-2,4-dicyano-5-(pyrrolidin-1-yl)selenophene with phenyl isothiocyanate, followed by S-alkylation, a series of functionalized derivatives were synthesized.[2] A complementary study extends this methodology to synthesize [1,3]selenazolo[5,4-e][1,2,4]triazolo[1,5-c]pyrimidines through acidic and basic Dimroth rearrangements. Starting from a selenazolo-pyrimidine scaffold, the strategy involves hydrolysis, cyclization, and selective alkylation.[3] These studies collectively highlight the immense potential of selenium-containing heterocycles in anticancer and antioxidant applications, demonstrating the influence of structural modifications on bioactivity. The findings contribute to the growing interest in selenium-enriched frameworks for developing innovative therapeutic agents targeting oxidative stress, cancer, and other diseases.

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