Fig. 4: Bidirectional stereospecific positional alkene isomerization to axially chiral N-indolylquinolinones.

Reaction conditions: DBN (0.1 mmol, 0.1 mmol/mL) was rapidly added to 1a (0.1 mmol) in 1,4-dioxane (5 mL), or DABCO (0.025 mmol, 0.1 mmol/mL) was rapidly added to 1a (0.1 mmol) in MeOH (5 mL) at rt for 5–10 min. Isolated yield, the ee values were determined by chiral HPLC.