Ecofriendly Synthesis of Formamidine Derivatives Catalyzed by Al-MCM-41 Mesoporous Materials

Formamidine derivatives have been synthesized in excellent yields at room temperature from primary amine and N,N-dimethylformamide dimethylacetal (DMF-DMA) in the presence of a catalytic amount of Al-MCM-41 synthetized from natural bentonite as silica and aluminum source. The advantages of this method are the use of a cheap, stable, non-toxic, and readily available catalyst, easy work-up, improved yields, and solvent-free conditions.

Synthesis of Enaminones-Based Benzo[d]imidazole Scaffold: Characterization and Molecular Insight Structure

(E)-1-(1H-Benzo[d]imidazol-2-yl)-3-(dimethylamino)prop-2-en-1-one 2 was synthesized by one-pot synthesis protocol of 2-acetyl benzo[d]imidazole with dimethylformamide dimethylacetal (DMF-DMA) in xylene at 140 °C for 8 h. Reaction of enaminone derivative 1 with acetylacetone in the presence of AcOH/NH4OAc under reflux afforded the cyclized pyridino-benzo[d]imidazole derivative 3. The latter compound was converted into the corresponding β-enaminone 4 with DMF-DMA. The single crystal X-ray diffraction technique eventually confirmed the assigned chemical structure of the N-alkyl-β-enaminone 2 and pyridino-benzo[d]imidazole derivative 3. N-alkyl-β-enaminone 2 crystallized in the monoclinic space group P21/n with unit cell parameters of a = 9.8953(3) Å, b = 5.7545(2) Å, c = 21.7891(7) Å, and β =100.627(2)°, and with one molecule per asymmetric unit. On the other hand, compound 3 crystallized in the orthorhombic crystal system and space group P212121 with unit cell parameters of a = 6.82950(10) Å, b = 8.00540(10) Å, c = 22.4779(2) Å, and also with one molecule per asymmetric unit. Based on Hirshfeld analysis, the H...H (51.3%), O...H (10.0%), N...H (10.3%), and C...H (27.6%) contacts in 2 and the H...H (46.8%), O...H (9.9%), N...H (13.0%), and C...H (21.6%) in addition to the C…C (6.7%) interactions in 3 are the most important towards crystal stability via molecular packing. The main difference is the presence of π–π interaction among the molecular units of 3 but not in 2. The calculated 1H and 13C NMR chemical shifts showed good agreements with experimental data. Electronic properties and reactivity parameters of both compounds are also calculated and compared.

Synthesis and Biological Evaluation of Pyrido(2,3-d)pyrimidines

: There are four types of pyridopyrimidines namely pyrido[2,3-d], pyrido[3,4-d], pyrido[4,3-d]pyrimidines, and pyrido[3,2- d]pyrimidines. Different methods of preparation of pyrido[2,3-d]pyrimidines are summarized. Synthesis of pyrido[2,3-d]pyrimidines can be from pyrimidines derivatives or pyridine derivatives. We can start from pyrimidine derivatives and build pyridine ring. 5,7- Diphenylpyrido[2,3-d]pyrimidines 3 and 4 were obtained by the reaction of 6-aminouracil (1) with α,β-unsaturated ketone. 6-Amino-1,3- dimethyluracil 10 was reacted with equimolar amount of Mannich bases 11a-c under an atmosphere of nitrogen to give pyridopyrimidines 14a-c via the formation of the intermediates 12a-c& 13a-c. 4-Benzylamino derivative 19 could be converted to pyrido[2,3-d]pyrimidine derivative 20 by the reaction with dimethylformamide/ dimethylacetal. In the same way, we can start from pyridine derivatives and build pyrimidine ring. Different reported biological activities of pyrido[2,3-d]pyrimidines are discussed e.g. selective adenosine kinase inhibitors, analgesic, anti-inflammatory, antimicrobial and herbicides, selective inhibitor of the tyrosine kinase activities of the fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF) receptors.

Biginelli Synthesis of Novel Dihydropyrimidinone Derivatives Containing Phthalimide Moiety

A new series of novel Biginelli compounds, 5-benzoyl-substituted phenyl-3,4-dihydropyrimidin-2(1H)-one-1H-isoindole-1,3(2H)-dione (1−10), were synthesized from enaminone, 2-{4-[(2E)-3-(dimethylamino)prop-2-enoyl]phenyl}-1H-isoindole-1,3(2H)-dione (IV), which was synthesized by refluxing 2-(4-acetylphenyl)-1H-isoindole-1,3(2H)-dione (III), with dimethylformamide-dimethylacetal (DMF-DMA) without solvent for 12 h. The compound 2-(4-acetylphenyl)-1H-isoindole-1,3(2H)-dione (III) was obtained by reacting phthalic anhydride (I) with para-aminoacetophenone (II) in glacial acetic acid for 2 h. The dihydropyrimidinone derivatives containing phthalimide moiety (1–10) were obtained by reacting enaminone, 2-{4-[(2E)-3-(dimethylamino) prop-2-enoyl] phenyl}-1H-isoindole-1,3(2H)-dione (IV), with urea and different substituted benzaldehydes in the presence of glacial acetic acid for 3 h. Simple and efficient method was employed to synthesize the dihydropyrimidinone derivatives containing phthalimide moiety. Structures of all the synthesized compounds were characterized by spectroscopic methods.

An efficient ultrasonic-mediated one-pot synthesis of 2,3,6,7,9-pentaazabicyclo[3.3.1]nonanes via a N,N-dimethylformamide dimethylacetal catalyzed Mannich-like reaction

A novel and straightforward method for one-pot synthesis of functionalized 2,3,6,7,9-pentaazabicyclo[3.3.1]nonane derivatives has been developed.