Synthesis of new substituted 7-azaisoindigos

7-Azaisoindigo is an important member of bisoxindole family, which has already shown to exhibit biological activities (as anti-inflammatory, antioxidant, antibacterial, antiviral, immunomodulatory) and has been employed in the synthesis of conjugates and polymers with promising electronic properties. However, articles focusing the preparation of this structure are rare and the number of derivatives described is still low. In order to expand the these starting materials, we report here the syntheses of new substituted 7-azaisoindigos. The strategy employed was an acid-catalyzed coupling reaction between 7-azaoxindole and substituted isatins. ZrCl4 in refluxing ethanol as a catalyst showed better results and permitted the syntheses of 6 new 7-azaisoindigos derivatives (R = Cl, Br, and NO2) in yields ranging from 27 to 60%.

Automated summary

7-Azaisoindigo is an important member of the bisoxindole family with various biological activities and potential in electronic material synthesis. However, there is limited research on its preparation and few derivatives have been reported. This study successfully synthesized six new substituted 7-azaisoindigos using an acid-catalyzed coupling reaction between 7-azaoxindole and substituted isatins with ZrCl4 as a catalyst in refluxing ethanol.