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

Abstract

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.