Yasuhiro Okuda, Takuma Sato, Sou Takebe, Matsuri Mori, Mayo Fujimoto, Kazunori Masuda, Taisei Sabato, Kan Wakamatsu, Haruo Akashi, Akihiro Orita
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A chemodivergent synthesis of polycyclic aromatic diarylamines and carbazoles was established by employing thermally or photochem. controlled processes using KOtBu/1,10-phenanthroline. The synthetic processes involved the dephosphinylation of 9-amino-10-(phosphinyl)phenanthrenes, which were obtained through a regioselective palladium-catalyzed direct [4 + 2] benzannulation of phosphinyl ynamines with 2-iodobiphenyls. When the dephosphinylation was conducted under heating conditions (~100°C), it proceeded to yield 9-aminophenanthrene. However, when the reaction was performed under the illumination of purple light (LEDs, λmax = ca. 390 nm), KOtBu/1,10-phenanthroline promoted single-electron-transfer-triggered dephosphinylation followed by cyclization, producing the corresponding π-expanded carbazoles. We successfully synthesized a highly π-expanded dicarbazole through a dual dephosphinylative cyclization. Addnl., we present the optical properties of a series of amino compounds produced through the dephosphinylative processes.
Research papers (academic journals)
