A 1,1'-bitriphenylene-based sila[7]helicene I [(+)-5, R = CH2OH] was prepd. synthesized with a high ee value by enantioselective double [2+2+2] cycloaddn. of a biaryl-linked tetrayne 2'-(HC竕｡C)C6H4C6H4-2-C竕｡CC竕｡C-2-C6H4C6H4-2'-(C竕｡CH) (3) with a silicon-linked bis(propargylic alc.) HOCH2C竕｡CSiMe2C竕｡CCH2OH (2) as a key step. The helicene 5 undergoes ring isomerization catalyzed by Rh(I)/(S)-Segphos complex, giving chiral biaryl II [(+)-4, R = CH2OH]. This sila[7]helicene 5 exhibited a high tolerance toward racemization, which could be explained by the x-ray crystal structure anal. With respect to the photophys. properties, this sila[7]helicene exhibited a relatively high fluorescence quantum yield and circularly polarized luminescence activity. [on SciFinder(R)]
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