selenation

Selenation is the chemical process of introducing selenium into a molecule, typically by forming a carbon–selenium bond or attaching a selenium-containing substituent. In organic synthesis, it covers diverse methods that transfer a selenium unit to a substrate, including electrophilic, nucleophilic, and radical approaches.

Electrophilic selenation uses selenium electrophiles such as organoselenium halides or related reagents to add Se to alkenes, alkynes, or arenes. Nucleophilic selenation employs organoselenium nucleophiles, including selenolates or diselenides under reducing conditions. Radical strategies use Se-centered radicals to functionalize unsaturated substrates.

Applications include synthesis of selenides and other Se-containing motifs for natural products, medicinal chemistry, and materials science. Selenation can enable downstream transformations such as oxidation to selenoxides or rearrangements that yield diverse organoselenium structures.

Reaction conditions vary from metal-catalyzed to metal-free, with attention to selectivity and minimization of selenium oxidation. Because many selenium compounds are toxic, safe handling and disposal are essential.

In older literature, selenation is sometimes used interchangeably with selenylation, but modern usage typically specifies the introduction of selenium into organic frameworks.