Calcium(II)‐Catalyzed Alkoxyselenation of 1,3‐Dienes With Selenium–Nitrogen Exchange Reagents

Organoselenium compounds are widely found in biologically active molecules and functional materials, yet efficient and selective selenofunctionalization of conjugated dienes remains underdeveloped. Herein, we report a calcium(II)‐catalyzed three‐component alkoxyselenation of 1,3‐dienes with benzothiaselenazole‐1‐oxides (BTSAs), a class of selenium–nitrogen exchange reagents, and alcohols as nucleophiles. This transformation proceeds under mild conditions and provides straightforward access to structurally diverse organoselenium compounds in moderate to good yields with excellent chemo‐, regio‐, and E‐selectivity. A broad range of aryl‐, heteroaryl‐, and alkyl‐substituted 1,3‐dienes, as well as structurally diverse BTSAs and alcohols, are well tolerated. The synthetic utility of this protocol is further demonstrated by late‐stage functionalization of complex molecules, gram‐scale synthesis, and downstream derivatization, highlighting its potential as a practical platform for the synthesis and diversification of bioactive organoselenium compounds.