世界最長級のπ拡張カルボ[17]ヘリセンの不斉合成に成功 ーベンゼン環17個のらせん構造の構築と赤色円偏光発光を実現ー

2026-10-16 東京科学大学

世界最長級のπ拡張カルボ[17]ヘリセン

＜関連情報＞

• https://www.isct.ac.jp/ja/news/3v8kwp0oe4xo
• https://www.nature.com/articles/s44160-026-01193-3

配列制御された四重[2+2+2]環化付加反応によるπ拡張カルボ[17]ヘリセンの鏡像選択的合成 Enantioselective synthesis of π-extended carbo[17]helicene via sequence-controlled quadruple [2+2+2] cycloadditions

Futo Morita, Takeshi Ichimura, Juntaro Nogami, Yuko Kishida, Kanato Takahashi, Ryota Shimizu, Hidehiro Uekusa & Ken Tanaka
Nature Synthesis  Published:14 October 2026
DOI:https://doi.org/10.1038/s44160-026-01193-3

Abstract

The enantioselective synthesis of giant chiral nanocarbons composed solely of carbon and hydrogen remains a central synthetic challenge. Increasing molecular strain, steric congestion and loss of cyclization sequence control have prevented access to enantioenriched long π-extended carbohelicenes. Here we report the enantioselective synthesis of a π-extended carbo[17]helicene enabled by a programmed precursor for quadruple [2+2+2] cycloadditions followed by oxidative annulations. The sterically differentiated dodecayne incorporates two inner triyne units forming less congested [5]helicenes and two outer triyne units forming sterically demanding [6]helicenes. These triyne units are separated by a triphenylene backbone that modulates steric demand and enforces sequence from the molecular centre. This sequence-controlled annulation suppresses dead-end pathways and enables stepwise assembly of the helicene framework with high enantioselectivity. The resulting carbohelicene exhibits circularly polarized luminescence with g_lum values of up to 0.043. This study highlights steric differentiation and cyclization programming as useful design strategies for the enantioselective synthesis of large helical nanocarbons.