Lewis Acids Catalyzed Annulations of Ynamides with Acyl Chlorides for Constructing 4‑Amino-2-naphthol Derivatives and 3‑Aminocyclobutenones

Two complementary synthetic manifestations
leading to highly substituted
1-naphthol and 2-naphthol derivatives via Lewis acids catalyzed annulations
of ynamides with acyl chlorides are described here. A one-pot synthesis
of 4-amino-2-naphthol derivatives is accomplished via a ZnI2-catalyzed tandem Friedel–Crafts reaction sequence. While
in the presence of Pd(0) catalyst, a [2 + 2] cycloaddition reaction
of ynamides with monosubstituted ketenes that were generated from
the dehydrohalogenation of suitable acyl chlorides leads to efficient
formation of 3-aminocyclobutenones, which were subsequently modified
to generate 3-amino-1-naphthols in excellent yields.