Key points are not available for this paper at this time.
Treatment of 2-allenyl indole 4 with a catalytic 1:2 mixture of (S)-2Au2Cl2 (S)-2 = (S)-3,5-tBu-4-MeO-MeOBIPHEP and AgBF4 in toluene at -10 degrees C for 17 h led to isolation of tetrahydrocarbazole 5 in 88% yield with 92% ee. The protocol was effective for the cyclization of terminally disubstituted allenes and for the formation of seven-membered rings.
Liu et al. (Thu,) studied this question.