Figure 18.
Heterocyclic helicene‐like compounds. Cyclization conditions: a) FeCl3 (6.6–12 equiv), CH2Cl2, CH3NO2, 0 °C; b) DDQ (4.5 equiv), BF3⋅Et2O, CH2Cl2, 0 °C; c) DDQ (5 equiv), Sc(OTf)3, toluene, reflux.
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