Synthesis of BODSe

BOD (400 mg, 13.5 mmol) and selenomorpholine [218 mg, 14.5 mmol, synthesized according to the reported method (Xu and Qian, 2019)] were added into a flask containing 10 mL DCM, which were stirred at room temperature, and the reaction was monitored by thin layer chromatography. After the reaction was finished, the solvent was removed, and the crude product was purified by silica gel column chromatography (hexane/EtOAc: 5:1–2:1) to obtain a deep red solid yield (330 mg, 60%). ¹H-NMR (400 MHz, CDCl₃) δ = 7.79 (d, J = 8.0, 1H), 7.75 (d, J = 8.3, 1H), 7.52 (t, J = 7.5, 1H), 7.32 (m, 2H), 7.06 (s, 1H), 5.93 (s, 1H), 4.43 (m, 4H), 3.06 (m, 4H), 2.49 (s, 3H), 2.26 (s, 3H). ¹³C-NMR (101 MHz, CDCl₃) δ = 143.85, 137.36, 130.63, 128.94, 128.44, 127.97, 126.60, 125.79, 123.74, 119.49, 114.74, 109.71, 54.52, 17.93, 11.03. HRMS: [M] calcd. for C₁₉H₂₀BF₂N₃Se: 419.0884; found 419.0892.