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13 C NMR chemical shifts (δ in ppm) for compounds 4a-g
Source publication
Reaction between 2-aminobenzimidazole 1, dimedone 2 and aldehydes 3 in ethanol afforded tetracyclic 12-aryl-3,3-dimethyl-3,4,5,12- tetrahydrobenzimidazo[2,1-b]quinazolin-1(2H)-ones 4a-g in good yields. The reactions were highly regioselective, what was established by nmr measurements.
Contexts in source publication
Context 1
... respectively. I3 C-nmr spectra (with DEPT-135 experiment) permitted the assignation of signals belonging to quaternary, tertiary, secondary and primary carbon atoms for compounds 4a-g (see Table 2). ...Citations
A novel series of 6‐acetyl‐[1,2,4]triazolo[1,5‐ a ]pyrimidines, hexahydro‐[1,2,4]triazolo[5,1‐ b ]quinazolines, tetrahydrobenzo[4,5]imidazo[2,1‐ b ]quinazolin‐1‐ones, and 3‐acetyl‐1,4‐dihydrobenzo[4,5]imidazo[1,2‐ a ]pyrimidines linked to phenoxy‐ N ‐arylacetamide moieties were prepared via Biginelli‐like cyclo‐condensation reaction of the 2‐(4‐formylphenoxy)‐ N ‐arylacetamides, with the appropriate active methylene containing reagents and nitrogen bi‐nucleophiles. Elements and spectroscopic data were used to confirm the compositions of the novel compounds. We proposed a reasonable mechanism for the creation of target products.
A novel regioselective synthesis of a series of bis(tetrahydrobenzimidazo[2,1-b]quinazolin-1-(2H)-ones) via the reaction of bis-aldehydes with two-mole equivalents of both dimedone and benzimidazole in DMF at reflux or under the effect of microwave heating is reported.
The molecular hybridization of various compounds with known pharmacological activity is a particularly popular approach for the development of potential drugs with improved pharmacokinetic profiles. In this respect, a novel series of bis(1,4-dihydropyridine-3,5-dicarbonitrile), bis(decahydroacridine), bis(tetrahydrodipyrazolo[3,4-b:4′,3′-e]pyridin), and bis(tetrahydropyrimido[4,5-b]quinoline-2,4,6-trione) derivatives linked to piperazine core via phenoxyethanone linkages were prepared via Hantzsch like reaction of the ((piperazine-1,4-diylbis(2-oxoethane-2,1-diyl))bis(oxy))dibenzaldehydes, with the appropriate active methylene containing reagents. Attempted synthesis of the target products via bis-alkylation of the appropriate phenol with 1,1′-(piperazine-1,4-diyl)bis(2-chloroethan-1-one) in different basic conditions were unsuccessful.
In this study, silica‐coated Fe3O4 nanoparticle@silylpropyl triethylammonium polyoxometalate catalyst was fabricated and characterized using atomic absorption, inductively coupled plasma optical emission spectrometry, elemental analysis, thermogravimetric analysis, Fourier‐transform infrared, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, and vibrating sample magnetometry analyses. The activity of this catalyst was examined in the synthesis of tetrahydrobenzimidazo[2,1‐b]quinazolin‐1(2H)‐ones. The bonding of the polyoxometalate to the surface of the nanoparticles exhibited excellent catalytic activity in this synthesis. Besides, the catalyst showed good reusability and recovery from the reaction mixture. Tetrahydrobenzimidazo[2,1‐b]quinazolin‐1(2H)‐ones were synthesized in high yields in the presence of inexpensive supported solid acid catalysts under classical heating conditions. Silica‐coated Fe3O4 nanoparticle@silylpropyl triethylammonium polyoxometalate catalyst was synthesized and utilized in the synthesis of tetrahydrobenzimidazo[2,1‐b]quinazolin‐1(2H)‐ones. The excellent catalytic activity was observed due to bonding of the polyoxometalate to the surface of the nanoparticles.
In this article, we report the preparation of a new ionic liquid from the reaction of DABCO and sulfuric acid and its characterization using FT-IR, Mass and NMR spectroscopy. This ionic liquid is air- and water-stable and affordable. Afterward this reagent is used for the synthesis of benzimidazoquinazolinone and pyrimido[4,5-b]-quinoline derivatives as a catalyst. The results show the applicability of the prepared reagent as a reusable catalyst without losing its activity. This procedure possesses some advantages such as ease of preparation of the catalyst, simple work-up procedure, short reaction times, excellent yields and use of nontoxic and inexpensive catalyst.
One-pot three-component synthesis of benzimidazo[2,1-b]-quinazolin-1-ones was efficiently performed under microwave irradiation and solvent-free condition. The method provides some advantages such as low cost, experimental simplicity, high yields, and short reaction times. The structure of newly synthesized compounds is characterized by IR, 1H-NMR, MS and elemental analysis.
This chapter explores that dimedone is a versatile precursor for annulated heterocycles. Dimedone(1) is an alicyclic compound having 1,3-dicarbonyl groups flanked by a methylene group and exists in a tautomeric transenolized form where intramolecular hydrogen bonding is not possible. Dimedone is an excellent precursor for partially hydrogenated fused heterocycles where two of the carbon atoms of dimedone are part of the backbone of the formed heterocycles. The chapter illustrates that dimedone's structural features and its reactivity to form more functionalized derivatives have led to the construction of a wide range of fused or spiral biheterocycles. Finally, this chapter emphasizes the role of 1 in the synthesis of fused heterocycles, classified according to the size of the ring and the number of heteroatoms in the heterocycle fused to the cyclohexane ring and subdivided according to the heteroatoms and their arrangement in the ring.
