Asymmetric Organocatalytic 1,6-Conjugate Addition of Alkynyl 8-Methylenenaphthalen-2(8H)-one Formed In Situ: Synergistic Construction of Axial and Central Chirality

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Organocatalytic enantioselective formal nucleophilic substitution reactions of α-(2-hydroxynaphthalen-8-yl)propargyl alcohols with 1-(1 H -indol-3-yl)naphthalen-2-ols have been established for the first time. With the aid of a suitable chiral phosphoric acid, alkynyl 8-methylenenaphthalen-2(8 H )-one was formed in situ from the corresponding α-(2-hydroxynaphthalen-8-yl)propargyl alcohol, followed by enantioselective 1,6-conjugate additions of 1-(1 H -indol-3-yl)naphthalen-2-ols to afford a number of enantioenriched ( R a, S c )-2,3-disubstituted indoles in 50–80% yields with 81–93% ee and ( S a, S c )-2,3-disubstituted indoles in 18–40% yields with 79–96% ee. Notably, these nucleophilic substitution products were characterized by the presence of functional groups, including indole, naphthol, and alkynyl units, while exhibiting both axial and central chirality.