Synthesis of Rigid Stepladder Polymers <i>via</i> Scandium-Catalyzed Polyspiroannulation of Quinoline with Alkyne
Jingjing Shao, Lin Huang, Shao‐Jie Lou, Aya Ohno, Yoichi M. A. Yamada, Masayoshi Nishiura, Tetsuro Murahashi, Zhaomin Hou
Abstract
Polymers with rigid three-dimensional architectures have attracted significant attention due to their high rigidity and intrinsic microporosity. Here, we report the synthesis of a new class of rigid stepladder polymers featuring unique spirodihydroquinoline skeletons. Under the catalysis of a half-sandwich scandium catalyst, quinoline compounds bearing both an aryl substituent (e.g., phenyl or naphthyl) and an alkynyl group (e.g., C≡CSiMe 3 ) selectively undergo dearomative polyspiroannulation between the quinoline skeleton and the alkyne unit via ortho -C–H activation of the aryl group. This reaction efficiently yields rigid stepladder polymers comprising a spirodihydroquinoline skeleton with a quaternary carbon stereocenter and an unprotected N–H group. Treatment of the N–H-containing polymers with an alkyl lithium reagent followed by methyl iodide leads to quantitative formation of the corresponding N -methylated polymers, which exhibit enhanced thermal stability and porosity compared to their N–H counterparts.