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

摘要

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 SnCl _2·2 H_2O 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 NH_2 group to both the formyl and carboxylic acid C=O groups.