“…Synthetic route for the synthesis of L1-L5. Method A [a] : CuSO 4 • 5H 2 O, sodium ascorbate, K 2 CO 3 , pyridine, water/t-BuOH, r.t., 3d; [13][14][15][16] Method B [b] : tetramethylazanium hydroxide, DMSO, r.t., 12 h; [17] Method C [c] : CH 3 I, MeCN, 70°C, 2d; [18] Method D [d] : Me 3 OBF 4 , DCM, r.t., 3d; [19] Method E [e] : Me 2 I 2 , AgOTf, hexane/toluene, refluxe, 12 h. [20] Scheme 2. Synthesis of the Mesoionic Carbene-Boranes.…”