Controlling the C(sp3)-C(sp2) Axial Conformation in the Enantioselective Friedel-Crafts-Type Alkylation of β-Naphthols with Inden-1-ones.

The Friedel-Crafts-type reaction between properly functionalized inden-1-ones and 2-naphthols generates a hindered single bond which displays a unique preference for an antiperiplanar conformational diastereoisomer. The steric hindrance and the presence of an enantioenriched stereogenic center control the distribution of the two diastereomeric conformers at equilibrium and increase the energy for the rotation of the C(sp3)-C(sp2) single bond.