Syntheses of 3-Hydroxy-1H-phenalen-1-ones from Methylthionaphthalenes with Malonic Acids

Abstract

3-Hydroxy-1 H-phenalen-1-ones were obtained by one pot reactions of 1- or 2-methylthionaphthalene with malonic acid or methylmalonic acid in polyphosphoric acid at 70°C for 3 h. By the reaction of 1- or 2-naphthalenethiol with malonic acid, hydroxynaphthothiopyranones were obtined in stead of 3-hydroxy-1 H-phenalen-1-ones. By the reactions with methylmalonic acid, 3-hydroxy-2-methyl-1 H-phenalen-1-ones were obtained. Furthermore, the corresponding oxygen-containing compounds were obtained by the reactions of methoxynaphthalenes or naphthols with malonic acid. The reaction path was discussed from the analysis of reaction products. These results shown that the reaction provides a useful method for the synthrses of substituted 1 H-phenalen-1-ones.