Efficient Synthesis of Substituted Aza-Anthraquinones via Michael Addition–Elimination and Intramolecular Cyclization Reactions under Mild Conditions and Their Fluorescent Properties

Abstract

In this study, a new approach for the synthesis of substituted aza-anthraquinones has been developed. The SnCl₂ catalyzed reaction of 2-amino-4H-chromen-4-one with 2-benzylidenemalononitriles provides the corresponding substituted aza-anthraquinone analogs via a Michael addition–elimination followed by intramolecular cyclization in good to excellent yields under mild reaction conditions. Furthermore, the synthesized compounds 3a–3l were analyzed for their preliminary photo physical properties (absorption and emission spectra) in CHCl₃ at 100 μM. Among the compounds (3a–3l), the compounds 3c and 3b exhibited larger emission band maxima toward bathochromic shifts at 488 nm and 468 nm, respectively.

Keywords:

• 2-Amino-4H-chromen-4-one
• aza-anthraquinones
• emission spectra
• fluorescent properties
• Michael addition–intramolecular cyclization
• SnCl₂ catalyzed