Organocatalytic γ,γ‐Regioselective Formal (1+5) Cycloaddition of Isoindolinone‐Derived Propargylic Alcohols

Abstract An organocatalytic γ,γ‐regioselective formal (1+5) cycloaddition of isoindolinone‐derived propargylic alcohols with 2‐indolylphenols was established, which afforded a series of indole‐fused chromanes with potential antitumor activity in overall good yields (up to 99 %). A tandem cycloaddition process was proposed based on detailed control experiments. Moreover, biological evaluation demonstrates the promising application of indole‐fused chromanes. This work not only established the first γ,γ‐regioselective (1+n) cycloaddition of isoindolinone‐derived propargylic alcohols, but also provided a good example of 1,5‐CO‐regioselective (5+1) cycloadditions involving 2‐indolylphenols for the synthesis of indole‐fused chromanes with potential biological activity.