Enantiospecific Synthesis of Imidazoquinazolin-2-ones via Base-Catalyzed Tandem Cyclization

A facile protocol for the enantiospecific synthesis of novel (S)-3-substituted imidazo[2, l-b]quinazoline-2-ones via tandem reaction of substituted (S)-3-amino-4-aminomethylbenzoates and cyanogen bromide under basic conditions is explored. This tandem process involves addition reaction of substituted (S)-3-amino-4-aminomethylbenzoates to CNBr to yield 2-imino tetrahydroquinazoline carboxylate intermediates followed by in situ intramolecular aminolysis to afford the triheterocyclic imidazo[2, l-b]quinazoline-2-ones in good yields and high enantiomeric purity.