Synthesis of fused benzimidazole–quinoxalinones via UDC strategy and following the intermolecular nucleophilic substitution reaction

A series of fused benzimidazole–quinoxalinones were synthesized utilizing a one-pot UDC (Ugi/de-protection/cyclization) strategy to form a benzimidazole group with subsequent intermolecular nucleophilic substitution reaction to form quinoxalinone functionality. Using combinations of either a tethered ketone acid or aldehyde acid input the Ugi reaction was shown to afford (1) a ring system through lactamization, (2) a benzimidazole through de-protection and cyclization, and (3) a quinoxalinone through the nucleophilic substitution reaction. Scaffolds were produced in good yields and facile operation.