Calcium(II)-Catalyzed Three-Component Alkoxyselenation of Allenes with Selenium–Nitrogen Exchange (SeNEx) Reagents

A calcium-catalyzed three-component alkoxyselenation of allenes using selenium-nitrogen exchange (SeNEx) reagents and alcohols has been developed. Under mild conditions, this transformation enables direct and efficient access to structurally diverse organoselenium compounds through simultaneous formation of C-Se and C-O bonds. The reaction exhibits broad substrate scope and good functional-group tolerance, accommodating a range of aryl-, heteroaryl-, sterically demanding, and alkyl-substituted allenes, as well as diverse benzothiaselenazole 1-oxides, ebselen, and several alcohol nucleophiles. Excellent chemo- and regioselectivity are observed throughout. Gram-scale experiments demonstrate the practicality of the protocol, while control experiments argue against a radical pathway. This work provides a practical calcium-catalyzed SeNEx approach for allene selenofunctionalization, enabling direct access to structurally enriched organoselenium scaffolds.