Synthesis of 2,3-Diarylquinoxaline Carboxylic Acids in High-Temperature Water

Abstract Aromatic carboxylic acids are prone to decarboxylate in high-temperature water (HTW). While the decarboxylation kinetics of several aromatic have been explored, studies on their compatibility with organic syntheses HTW scarce. Herein, we report hydrothermal synthesis (HTS) 2,3-diarylquinoxaline from 1,2-diarylketones and 3,4-diaminobenzoic acid. A detailed study reaction parameters was performed identify conditions towards minimal decarboxylation. Thirteen 2,3-diarylquinoxaline-6-carboxylic obtained at temperatures between 150–230 °C within 5–30 minutes. The reported feature comparable performance those classic syntheses, avoiding volatile solvents, strong toxic catalysts. Decarboxylated quinoxalines arise as side products variable amounts via direct To completely inhibit decarboxylation, show that suitable structural analogues acid can act starting compounds. Thus, ester hydrolysis methyl 3,4-diaminobenzoate deprotection di-Boc-protected 3,4-diminobenzoic be coupled HTS quinoxaline acids, while fully decarboxylated products.