Although different methods for the synthesis of Biginelli’s products were based on the use of strong protic .. Pyrimidine and its derivatives. A Mini Review: Biginelli Reaction for the Synthesis of Dihydropyrimidinones. Conference Pyrimidine Containing Derivatives Scheme 7. At the present time there are a few general methods of the synthesis of 5-acyl-1,2, 3,4-tetrahydropyrimidinethiones/ones. One of them is the Biginelli reaction.
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The benzaldehyd derivatives with substitution in aromatic ring with 4-chloro, 3,4-dimethox, 4-methoxy, 4-methyl, 3-nitro, 2-hydroxy, 5-bromohydroxy, 4-isopropyl and 4-hydroxy groups were reacted with thiourea and ethyl benzoylacetate in the presence of HCl or DABCO as a catalyst under reflux condition to prepare a series of tetrahydropyrimidine derivatives scheme1Table 3.
After reaction completion, the reaction mass was cooled and treated with crushed ice. An improved synthesis of Biginelli-type compounds via phase-transfer catalyst. The reaction progression was monitored using TLC, which syntheais that no reaction occurred [ 37 ].
Each concentration was repeated 4 times for each of the bacteria and the average results of inhibitory effects are illustrated in Table 1. Atul Kumar has reported first enzymatic synthesis for Biginelli reaction via yeast catalysed protocol in high yields. Except for compound 8, the other compounds did not show any inhibitory activity against E.
The reported reactions of hydrazine hydrate with pyrimidines 7a —7 c and 9a —9 c. We studied the action of hydrazine hydrate as N -nucleophile on Biginelli pyrimidine esters 4a — 4h. Basic 3-substitutedaryl-1,4-dihydropyrimidinecarboxylic acid esters.
De Oliveira et al. Kabil5 Nasser S. Melting points were determined with an Electrothermal digital apparatus and were uncorrected.
Solvent-Free Ring Cleavage Hydrazinolysis of Certain Biginelli Pyrimidines
As a part of our research in the synthesis of pyrimidine derivatives containing biological activities, some new tetrahydropyrimidine derivatives were synthesized via Biginelli blginelli using HCl or DABCO as a catalyst with good yields. Said1 Wagdy M.
This reaction was reported by Biginelli and Gazz in and was then catalyzed by acids [ 14 ]. To a solution of DHPMs 4a — h 0. Synthesis and evaluation of some new fluorinated hydroquinazoline derivatives as antifungal agents. The results are shown in Table 2. Table 1 Antibacterial activity of some synthesized compounds inhibition zones, mm.
Support for anN-Acyliminium Ion Intermediate1″. The proposed mechanism for the reaction of DHPM derivatives 4a — 4h with hydrazine hydrate. Open in a separate window. View at Google Scholar H. The nonisolable carbohydrazide intermediates are formed firstly followed by the intermolecular nucleophilic attack of terminal amino group of hydrazide function on sp 2 C6 rather than the sp 3 C4 to give the ring adduct which was produced as a final product.
The reaction mechanism of the Biginelli reaction is a series of bimolecular reactions leading to the desired dihydropyrimidinone.
The obtained solid product 16a — 16d was filtered, crystallized from ethanol, and finally dried. Michaels, Antibiotics Annualvol. Support Center Support Center. Performance standards for antimicrobial susceptibility testing.
Table of Contents Alerts. El Kerdawy et al. View at Google Scholar T. Determination of the minimum inhibitory concentration MIC values for some synthesized compounds against six microorganisms was carried out using disc diffusion method According to Table 3the best results were obtained in the presence of DABCO as a catalyst where the products were achieved with high yields and shorter reaction times.
In 1 H NMR spectra, all of the products showed a singlet peak at about 5. Reaction Kinetics and Pyrimidien Letters. This final step ensues a second condensation and results in the Biginelli compound.