Synthesis of Isoindolo[2,1-a]quinazoline-5,11-dione Derivatives via the Reductive One-Pot Reaction of N-Substituted 2-Nitrobenzamides and 2-Formylbenzoic Acids

Various isoindolo[2,1‐a]quinazoline‐5,11‐dione derivatives 3 were synthesized in good yields by means of the reductive reaction of N‐substituted 2‐nitrobenzamides 1 and 2‐formylbenzoic acids 2 in the presence of SnCl2⋅2 H2O under reflux in EtOH (Scheme, Table). The procedure needed two steps, the reduction of the nitro group of the 2‐nitrobenzamide and ring closure by nucleophilic addition of the NH2 group to both the formyl and carboxylic acid CO groups.