An Efficient and Modified Biginelli-Type Synthesis of 3,4-Dihydro-1H-indeno[1,2-d]pyrimidine-2,5-dione Using Phosphorous Pentoxide

A simple, clean and convenient one-pot method has been developed for the synthesis of 4-phenyl-3,4-dihydro-1H-indeno[1,2-d]pyrimidine-2,5-dione and 4-phenyl-2-thioxo-1,2,3,4-tetrahydro-5H-indeno[1,2-d]pyrimidine-5-one by multicomponent condensation of 1,3-indanedione, aromatic aldehydes and urea/thiourea using phosphorus pentoxide in ethanol under reflux conditions. The simple workup procedure and moderate to good yields within short time are some important features of this protocol. The synthesized compounds have been interpreted on the basis of their spectroscopic data.