One-Pot Synthesis of 3,4-Dihydropyrimidino[2,1-a]isoindol-6(2H)-one

A one-pot synthesis of 3,4-dihydropyrimidino[2,1-a]isoindol-6(2H)-one, an analog of the promising anticancer drug batracylin, involving the acylation of 1,3-diaminopropane with phthalic anhydride followed by cyclocondensation under heating in toluene or o-xylene, was developed. The highest yield of the target isoindolone of 76% was obtained by adding 1,3-diaminopropane to phthalic anhydride in toluene, while when the order of reagent addition was reversed, the yield decreased to 60%. The reaction occurred stepwise through the formation of 2-[(3-aminopropyl)carbamoyl)]benzoic acid and its subsequent conversion to isoindolone under heating in a yield of 68%.