Insights into microwave‐promoted synthesis of 3‐methyl‐4‐phenyl‐4,9‐dihydro‐1H‐pyrazolo[3,4‐d][1,2,4]triazolo[1,5‐a]pyrimidine derivatives catalyzed using new Pd (II),Cu (II),VO (II), and Ag(I) complexes as a heterogeneous catalyst and computational studies

• Published in: Applied organometallic chemistry Vol. 38; no. 8
• Main Authors: Ali El‐Remaily, Mahmoud Abd El Aleem Ali, Alzubi, Mohammad Saleh Hussein, El‐Dabea, Tarek, El‐Khatib, Rafat M., Kamel, Moumen S., Feizi‐Dehnayebi, Mehran, Abu‐Dief, Ahmed M.
• Format: Journal Article
• Language: English
• Published: 01-08-2024
• Subjects: 5‐aminotetrazole; economy; green synthesis; Lewis acids; microwave; mild conditions; one‐pot reaction; spectral studies
• ISSN: 0268-2605; 1099-0739
• DOI: 10.1002/aoc.7587

Four novel Pd (II), Cu (II), VO (II), and Ag(I) complexes were prepared from benzimidazole ligand through bidentate chelating mode. Alternative spectral and analytical tools were applied to elucidate their structural and molecular formulae. This study was extended to investigate stability and stoichiometry of complexes in solution, using standard methods. In addition, the best atomic distribution within structural forms was obtained via the density functional theory (DFT) method. This computational study fed us with significant physical characteristics for differentiation. Also, DFT/time‐dependent DFT computations were performed applying (B3LYP/6‐311++G[d,p]/aug‐cc‐pVTZ/aug‐cc‐pVTZ‐PP) level in order to investigate the electronic behavior of the compounds. These results demonstrated good agreement with the experimental data. Computational data discriminate Pd (II) complex by some physical features, which may be promising in the catalytic field. This complex was selected to play a catalytic function to synthesize 3‐methyl‐4‐phenyl‐4,9‐dihydro‐1H‐pyrazolo[3,4‐d][1,2,4]triazolo[1,5‐a]pyrimidine derivatives using microwave irradiation in a one‐pot reaction. The catalyst was selected for this application based on the history of Pd (II) complexes and the properties expected theoretically. A condensation reaction for 3‐methyl‐5‐pyrazolone, aromatic aldehyde, and 5‐aminotetrazole was carried out under mild reaction conditions by microwave irradiation. All reaction conditions were optimized among those variable Lewis acid catalysts in comparison with our new complexes. DOBPAPd catalyst displayed superiority in overall trials with high yield, short time, and green conditions (solvent H2O/EtOH). Also, the recovery of hetero catalyst was succeeded and reused by the same efficiency up to five times after that the efficiency was reduced. The mechanism of action was proposed based on the ability of Pd (II) for adding extra‐bonds over z‐axis and supported by theoretical aspects.
The four metal chelates were synthesized from DOBPA ligands that were formed through fusion of benzimidazole guanidine and acetyl acetone. These chelates were chosen to play a catalytic behavior to synthesize 3‐methyl‐4‐phenyl‐4,9‐dihydro‐1H‐pyrazolo[3,4‐d][1,2,4]triazolo[1,5‐a]pyrimidine derivatives using microwave irradiation in a one‐pot reaction. A condensation reaction was taken on three components of 3‐methyl‐5‐pyrazolone, aromatic aldehyde, and 5‐aminotetrazole in (H2O/EtOH, [1:3]) solvent and was achieved in the presence of studied chelates under microwave (MW) conditions.