The cyclization of a series of nonheterocyclic allenyl aryl ketones was examined using boron trifluoride etherate and indium triflate to mediate the reaction. Yields with BF3 were low in most instances due mainly to competitive destruction of the substrates. With In­(OTf)3, there was less decomposition, and the yields of the cyclized product were much higher, but only for substrates with electron-donating substituents. Cyclization did not occur without those substituents. A computational study using the ωB97X-D/6-311+G­(2d,p)//ωB97X-D/6-31+G­(d,p) method confirmed better stability of the σ-complexed substrate by indium­(III) and that meta-substituents on the phenyl ring of the substrate significantly influenced the activation barrier of the cyclization, whereas the effect of para-substituents was almost negligible. The computational results supported the idea that the cyclization is a 4π-electrocyclization and not a 5-endo-dig ring closure as had been proposed in the literature.

Pyrimido [4,5-d] pyrimidine is an uracil compound that has similarities to the structure of pteridine and purines and has significant bioactivity. The aim of this research is to synthesize pyrimido [4,5-d] pyrimidine derivatives and test their activity as antioxidant. The reaction was carried out with the support of the iodine catalyst to get an effective reaction. Experimental evidence in support of the formation products was confirmed using FTIR, UV-vis Spectrophotometer, and GC-MS. The results of the analysis produced four pyrimido [4,5-d] pyrimidine derivatives, 5-Styryl-5,8-dihydro-1H,6H-pyrimido[4,5-d]pyrimidine-2,4,7-trione (compound 1), 5-Styryl-7-thioxo-5,6,7,8-tetrahydro-1H-pyrimido[4,5-d]pyrimidine-2,4-dione (compound 2), 5-Phenyl-5,8-dihydro-1H,6H-pyrimido[4,5-d]pyrimidine-2,4,7-trione (compound 3), and 5-Phenyl-7-thioxo-5,6,7,8-tetrahydro-1H-pyrimido[4,5-d]pyrimidine-2,4-dione (compound 4). Reaction optimization was conducted by varying reaction time, reaction temperature, amount of catalyst and solvent. The optimum conditions of the reaction were obtained under conditions of 10 % mol of catalyst, temperature 70 °C, for 4 h with a water solvent. Compound 1 has a better activity than 3 other compounds with an IC50 value of 10.11 ppm.