Photoinduced reactions have received much attention as a powerful tool to access kinetically or thermodynamically prohibited reactions on the ground state. However, these reactions have been developed mainly by using electro-negative elements such as C, O, N, halogens as well as transition-metals. On the other hand, we have revealed the nature of chemical species including electro-positive main-group elements, such as boron (B), silicon (Si), and tin (Sn), on the excited state, developing the highly reactive and selective photoinduced reactions. For diboron (B-B) reagents, we designed the anionic photo-absorbing borate complex to enable a quadruple borylation reaction of terminal alkynes under ultraviolet irradiation. For stannyl (Sn) species, we revealed that the illumination of stannyl anions generates the excited triplet stannyl diradicals, which showed the orthogonality to traditional reagents (cations, anions, and radicals) to enable hydrostannylation of alkynes and defluorostannylation of fluoroarenes. For silylborane (Si-B) reagents, we developed dearomative triple elementalization (carbo-silaboration) reactions of quinolines by the excitation of silyl-borate complexes without the need for any catalyst.

π共役高分子は光·電子材料として種々の応用が期待される機能材料であり，n型やp型半導体特性，バンドギャップ，発光挙動など，目的に応じて様々な光·電子特性をもつπ共役高分子が要求されている．このような材料を得るためには，高分子の繰返し単位への適切な化学構造の付与が必要である．π電子系に元素ブロックを付与すると，元素部位とπ共役系との軌道間相互作用による効果的な光·電子特性の発現が見込まれるが，合成化学的な制約からまだ十分には検討が行われていない未開拓の材料といえる．ここでは，著者らが検討を進めている主鎖結合位置の規制された主鎖型反応性高分子を前駆体とした種々の元素ブロックをもつπ共役高分子の設計·合成に関する研究を概説し，それらの発光特性や，化学センサー，電子デバイス素子などへの応用の可能性を述べる．