Efficient Synthesis of New Pyrimido[5,4:5,6]pyrano[2,3-d]pyrimidine-2,4,6(1H,3H)-triones via the Tandem Intramolecular Pinner-Dimroth Rearrangement, and Their Antibacterial Activity

Synthesis of new 8-alkyl-5-aryl-1,3-dimethyl-5,7-dihydro-2H-pyrimido[5,4:5,6]pyrano[2,3-d]- pyrimidine-2,4,6(1H,3H)-triones by the high yield reaction of 7-amino-5-aryl-1,3-dimethyl-2,4-dioxo-1,3,4,5- tetrahydro-2H-pyrano[2,3-d]pyrimidine-6-carbonitriles with aliphatic carboxylic acids in the presence of POCl3 is presented. It is probable that synthesis of these new products proceeds via the tandem intramolecular Pinner-Dimroth rearrangement. The products are characterized by FT-IR, H-1, and C-13 NMR spectra and evaluated for their antibacterial activity against gram +ve bacteria (Staphylococcus aureus and Staphylococcus epidermidis) and gram-ve bacteria (Escherichia coli and Pseudomonas aeruginosa) using the disc diffusion method.