Catalytic Enantioselective Oxidative Dearomatization of 1‑Naphthols Using Chiral Iminium Salts

The catalytic enantioselective oxidative
dearomatization
of 1-naphthols
is achieved using chiral iminium catalysts. The developed method yields ortho-quinols in high yields (up to 94%) and with high enantioselectivity
(up to 99% enantiomeric excess (ee)) under mild conditions. The asymmetric
reaction, which affords the complete regioselective hydroxylation
of 1-naphthols at the ortho-position, requires a
chiral iminium catalyst with a binaphthyl structure. To demonstrate
applicability to wide range of substrates, we synthesized the core
skeleton of vanitaracin A, which exhibits antiviral activity against
hepatitis B. The developed reaction is therefore highly useful in
the synthesis of natural aromatic polyketides.