Yu-Tsen KuoChia-Yu YaoYi-Hung LiuMu-Jeng ChengJeffrey M. Farrell2025-04-212025-04-212025https://scholars.lib.ntu.edu.tw/handle/123456789/728365The syntheses and reactivities of 2-isocyanobiphenyl·BX3 adducts (X = I, Br, Cl) are reported. These adducts undergo unexpected C-H bond-functionalizing cyclization upon heating, yielding phenanthridinium-6-trihaloborate zwitterions. Where X = Cl, an unexpected helical polycyclic boronium salt is formed via a competing pathway. Mechanistic details are probed experimentally and computationally.enjournal article10.1039/d5dt00210a