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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However, C5 esters reacted with hydrazine hydrate, in ethyl alcohol and in the presence of H 2 SO 4to give hydrazides 5 [ 3738 ] Figure 1.
InAtwal et al.
Tested compounds were dissolved in dimethyl sulfoxide DMSO for the preparation of stock solution. The Biginelli reaction is one of the simple and direct methods for the synthesis of tetrahydropyrimidines, originally reported by Biginelli 7.
To a solution of DHPMs 4a — h 0. Melting points were measured with a Stuart melting point apparatus and were uncorrected. On the other hand, when R 5 is an ester group, free carboxylic acids can be produced [ 32 — 34 ].
De Oliveira et al. View at Google Scholar K.
A New Synthesis of Biginelli Compounds
Table 3 Characterization data of tetrahydropyrimidine derivatives Normal saline was used for preparation of inoculants having turbidity equal to 0. Recently, we reported a unique behavior of hydrazine hydrate towards certain benzofurans to produce phenolic-based pyrazoles [ 42 ]. Except for compound 8, the other compounds did not show any inhibitory activity against E.
Heterocyclic compounds containing a pyrimidine nucleus are of special interests thanks to their applications in medicinal chemistry as they are the basic skeleton of several bioactive compounds such as antifungal, antibacterial, antitumor and antitubercular.
The remaining solid was filtered, washed with water and ethanol and it was consequently dried and recrystallized using ethanol. Correspondence should be addressed to Hazem A.
Bismuth III -catalyzed synthesis of dihydropyrimidinones: From Wikipedia, the free encyclopedia. Tetrahydropyrimidine, antimicrobial activity, Synhhesis reaction. In general terms, this report is going to describe the synthesis of new tetrahydropyrimidine derivatives via the Biginelli reaction using HCl or DABCO as a catalyst in ethanol.
A New Synthesis of Biginelli Compounds
Table 1 Antibacterial activity of some synthesized compounds inhibition zones, mm. Table of Contents Alerts.
Chemical shifts are expressed in values ppm using the solvent peak as internal standard. Experimental Melting points were determined with an Electrothermal digital apparatus and were uncorrected.
Regarding the importance of the Biginelli reaction products, much work on improving the yield and reaction conditions has been actively pursued. Synthesis of some novel chromenopyrimidine derivatives and evaluation of their biological activities. This reaction was developed by Pietro Biginelli in The latter data stimulate our interest to investigate the reactivity of C5 ester towards hydrazine hydrate under solvent-free conditions which produce three different ring cleavage products.
Certain Biginelli pyrimidines with ester substitution in C5 were subjected to unexpected ring opening upon solvent-free reaction with hydrazine hydrate to give three products: Views Read Edit View history.
The obtained solid product 16a — 16d was filtered, crystallized from ethanol, and finally dried. A mixture of an ethyl benzoylacetate 1 mmolaromatic aldehyde 1 mmolthiourea 1 mmol and an amount of concentration Hydrochloric acid or DABCO 0. In 1 H NMR spectra, all of the products showed a singlet peak at about 5. A mixture of DHPMs 4a — 4h 0. Oliver “The Biginelli Reaction”, in: Interestingly, the reported findings revealed that the hydrazinolysis of pyrimidine-2 1 H -one 7a4-methylpyrimidin-2 1 H -one 7bor 4,6-dimethylpyrimidin-2 1 H -one 7c resulted in the formation of 1 H -pyrazole 8a3-methyl-1 H -pyrazole 8b and 3,5-dimethyl-1 H -pyrazole 8crespectively, in addition to urea 1a in each case Figure 2 [ 40 ].
These facts showed the reactivity of sp 2 C6 of pyrimidines towards hydrazine hydrate and, subsequently, the ring opening of pyrimidine moiety.
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 broad absorption band for stretching vibration of NH groups was detected in the region cm The nucleophilic addition of urea gives the intermediate 4which quickly dehydrates to give the desired product 5.
General procedure for synthesis of tetrahydropyrimidine derivatives A mixture of an ethyl benzoylacetate 1 mmolaromatic aldehyde 1 mmolthiourea 1 mmol and an amount of concentration Hydrochloric acid or DABCO 0.