Nasser R. El-Brollosy

Synthesis of Novel Uracil Non‐Nucleoside Derivatives as Potential Reverse Transcriptase Inhibitors of HIV‐1

Novel emivirine and TNK‐651 analogues 5a–d were synthesized by reaction of chloromethyl ethyl ether and / or benzyl chloromethyl ether, respectively, with uracils having 5‐ethyl and 6‐(4‐methylbenzyl) or 6‐(3,4‐dimethoxybenzyl) substituents. A series of new uracil non‐nucleosides substituted at N‐1 with cyclopropylmethyloxymethyl 9a–d, 2‐phenylethyloxymethyl 9e–h, and 3‐phenylprop‐1‐yloxymethyl 9i–l were prepared on treatment of the corresponding uracils with the appropriate acetals 8a–c. Some of the tested compounds showed good activity against HIV‐1 wild type. Among them, 1‐cyclopropylmethyloxymethyl‐5‐ethyl‐6‐(3,5‐dimethylbenzyl)uracil 9c and 5‐ethyl‐6‐(3,5‐dimethylbenzyl)‐1‐(2‐phenylethyloxymethyl)uracil 9g showed inhibitory potency equally to emivirine against HIV‐1 wild type. Furthermore, compounds 9c and 9g showed marginal better activity against NNRTI resistant mutants than emivirine.

Synthesis of novel uracil non-nucleosides analogues of 3,4-dihydro-2-alkylthio-6-benzyl-4-oxopyrimidines and 6 -benzyl -1 -ethoxymethyl -5 -isopropyluracil

A series of new uracil non-nucleosides analogues of S-DABOs was synthesised by reaction of 5-alkyl-6-(p-chlorobenzyl)-2-thiouracils with chloroethyl dialkylamine hydrochloride, N-(2-chloroethyl)-pyrrolidine hydrochloride, N-(2-chloroethyl)-piperidine hydrochloride or appropriate haloethers. Novel emivirine analogues were synthesised by silylation of 5-alkyl-6-(p-chlorobenzyl)uracils and treatment with bromomethyl methyl ether, chloromethyl ethyl ether or benzyl chloromethyl ether. Compounds 6-(p-chlorobenzyl)-5-ethyl-1-ethyloxymethyluracil (9e) and 1-benzyloxymethyl-6-(4-chlorobenzyl)-5-ethyluracil (9f) showed activity against wild-type HIV-1 strain III B in MT-4 cells.

Synthesis and Antimicrobial Activity of Some Novel 5-Alkyl-6-Substituted Uracils and Related Derivatives

6-Chloro-5-ethyl-, n-propyl- and isopropyluracils 5a-c were efficiently prepared from the corresponding 5-alkybarbituric acids 3a-cvia treatment with phosphorus oxychloride and N,N-dimethylaniline to yield the corresponding 5-alkyl-2,4,6-trichloro-pyrimidines 4a-c, which were selectively hydrolyzed by heating in 10% aqueous sodium hydroxide for 30 minutes. The reaction of compounds 5a-c with 1-substituted piperazines yielded the corresponding 5-alkyl-6-(4-substituted-1-piperazinyl)uracils 6a-j. The target 8-alkyltetrazolo[1,5-f]pyrimidine-5,7(3H,6H)-diones 7a-c were prepared via the reaction of 5a-c with sodium azide. Compounds 6a-j and 7a-c were tested for in vitro activities against a panel of Gram-positive and Gram-negative bacteria and the yeast-like pathogenic fungus Candida albicans. Compound 6h displayed potent broad-spectrum antibacterial activity, while compound 6b showed moderate activity against the Gram-positive bacteria. All the tested compounds were practically inactive against Candida albicans.

Vibrational spectra, NBO analysis, HOMO-LUMO and first hyperpolarizability of 2-{[(2-Methylprop-2-en-1-yl)oxy]methyl}-6-phenyl-2,3,4,5-tetrahydro-1,2,4-triazine-3,5-dione, a potential chemotherapeutic agent based on density functional theory calculations.

The experimental FT-IR and FT-Raman spectra of 2-{[(2-Methylprop-2-en-1-yl)oxy]methyl}-6-phenyl-2,3,4,5-tetrahydro-1,2,4-triazine-3,5-dione were recorded. The optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of the compound have been examined by means of density functional theory. Reliable vibrational assignments and molecular orbital have been investigated by the potential energy distribution and natural bonding orbital analyses, respectively. The calculated first hyperpolarizability of the title compound is 2.82×10(-30) esu which is 21.69 times that of the standard NLO material urea. MEP was performed by the B3LYP level and the predicted infrared intensities and Raman activities have also been reported. Quantum chemical parameters were arrived from the frontier molecular orbital theory. The calculated geometrical parameters are in agreement with experimental results. From the MEP it is evident that the negative charge covers the CO groups and the positive region is over the rings and NH group.

Pyrimidine-5-carbonitriles - part III: synthesis and antimicrobial activity of novel 6-(2-substituted propyl)-2,4-disubstituted pyrimidine-5-carbonitriles

Abstract The reaction of 6-(2-methylpropyl or 2-phenylpropyl)-2-thiouracil-5-carbonitriles (4a,b) with various arylmethyl halides, 2-bromoethyl methyl ether, benzyl chloromethyl ether, and 2-bromomethyl-5-nitrofuran in N,N-dimethylformamide or acetone yielded the corresponding substituted thio-3,4-dihydro-4-oxopyrimidine-5-carbonitrile analogues 5a–h, 6a,b, 7, and 8a,b, respectively. Treatment of 5c with phosphorus oxychloride and N,N-dimethylaniline yielded the 4-chloropyrimidine derivative 9, which was allowed to react with various arylthiols, arylamines, and 1-substituted piperazines to yield the respective 4-arylthio 10a–d, 4-arylamino 11a–d, and 4-piperazino 12a,b derivatives. The newly synthesized compounds were tested for in vitro activities against a panel of Gram-positive and Gram-negative bacteria and the yeast-like pathogenic fungus Candida albicans. Compounds 5e, 5f, 5g,h, 7, 8a,b, and 12a display marked antibacterial activity, particularly against the Gram-positive bacteria. None of these compounds are active against C. albicans.

Pyrimidine-5-carbonitriles II: Synthesis and Antimicrobial Activity of Novel 6-Alkyl-2,4-disubstituted pyrimidine-5-carbonitriles

New series of 6-alkyl-2,4-disubstituted pyrimidine-5-carbonitriles namely, 6-alkyl-2-thiouracil-5-carbonitriles 4c,d, 6-alkyl-2-arylmethylsulfanyl-3,4-dihydro-4-oxopyrimidine-5-carbonitriles 5a-p, 6-alkyl-2-(2-methoxyethylsulfanyl)-3,4-dihydro-4-oxopyrimidine-5-carbonitriles 6a-d, 6-alkyl-2-benzyloxymethylsulfanyl-3,4-dihydro-4-oxopyrimidine-5-carbonitriles 7a-c, 6-alkyl-2-(5-nitrofuran-2-ylmethylsulfanyl)-3,4-dihydro-4-oxopyrimidine-5-carbonitriles 8a-d, 6-alkyl-4-arylthio-2-(benzylsulfanyl)pyrimidine-5-carbonitriles 10a, b and 2-benzylsulfanyl-4-[4-(2-methoxyphenyl)-1-piperazinyl]-6-pentylpyrimidine-5-carbonitrile 11, were synthesized and tested for in vitro activities against a panel of Gram-positive and Gram-negative bacteria and the yeast-like pathogenic fungus Candida albicans. Compounds 4d, 5b, 5c, 5d, 5e, 5f, 5g, 5h, 5i, 5j, 5k, 5 l, 5p, 7a, 7b, 7c, 8a, 8b, 8c, 8d and 11 -displayed marked antibacterial activity particularly against the tested Gram-positive bacteria. Meanwhile, none of these compounds were proved to be active against Candida albicans.

Some Observations on the Base-Catalyzed Cyclocondensation of 2,6-Dihalobenzaldehydes, Ethyl Cyanoacetate, and Thiourea

The reaction of 2,6-difluorobenzaldehyde, 2-chloro-6-fluorobenzaldehyde, or 2,6-dichlorobenzaldehyde and ethyl cyanoacetate and thiourea, in the presence of potassium carbonate, yielded a mixture of the cis- and trans-5,6-dihydro-2-thiouracil derivatives 4a–c. Compounds 4a–c, which were found to be resistant to atmospheric oxidation even at high temperatures, were successfully dehydrogenated to 5a–c via prolonged heating with chloranil in toluene. Meanwhile, oxidation of the dihydro derivative 4b by heating in dimethylsufphoxide for 10 min yielded the corresponding 2-thiouracil 5b in 73% yield, in addition to the disulfide derivative 7 as a minor product.

Theoretical investigations on the molecular structure, vibrational spectra, HOMO-LUMO analyses and NBO study of 1-[(Cyclopropylmethoxy)methyl]-5-ethyl-6-(4-methylbenzyl)-1,2,3,4-tetrahydropyrimidine-2,4-dione.

The FT-IR and FT-Raman spectra of 1-[(Cyclopropylmethoxy)methyl]-5-ethyl-6-(4-methylbenzyl)-1,2,3,4-tetrahydropyrimidine-2,4-dione were recorded. In this work, experimental and theoretical study on the molecular structure and vibrational wavenumbers of the title compound are presented. The vibrational wavenumbers were obtained theoretically at the DFT level and were compared with the experimental results. The study is extended to calculate the HOMO-LUMO energy gap, NBO, mapped molecular electrostatic potential and first hyperpolarizability. The calculated first hyperpolarizability of the title compound is 9.15 times that of urea and hence the title compound and the series of compounds it represents are attractive candidates for further studies in non linear optical applications. In the title compound, the HOMO of π nature is delocalized over the phenyl ring while the LUMO is located over the pyrimidine ring. The inter-molecular hydrogen bonding at O7 and N1H25 positions in each monomer give rise to a C2-symmetry dimer which is predicted to be about 10kcalmol(-1) more stable than the monomeric form.

Vibrational spectroscopic (FT-IR and FT-Raman) studies, HOMO–LUMO, NBO analysis and MEP of 6-methyl-1-({[(2E)-2-methyl-3-phenyl-prop-2-en-1-yl]oxy}methyl)-1,2,3,4-tetra-hydroquinazoline-2,4-dione, a potential chemotherapeutic agent, using density functional methods

6-Methyl-1-({[(2E)-2-methyl-3-phenyl-prop-2-en-1-yl]oxy}methyl)-1,2,3,4-tetra-hydro quinazoline-2,4-dione was prepared via treatment of silylated 6-methylquinazoline-2,4-dione with bis-[(E)-2-methyl-3-phenylallyloxy]methane. FT-IR and FT-Raman spectra were recorded and analyzed. The vibrational wavenumbers were computed using DFT methods and are assigned with the help of potential energy distribution method. The first hyperpolarizability, infrared intensities and Raman activities also reported. The geometrical parameters of the title compound obtained from XRD studies are in agreement with the calculated (B3LYP) values. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The HOMO and LUMO analysis are used to determine the charge transfer within the molecule. MEP was performed by the B3LYP method and from the MEP it is evident that the negative charge covers the CO group and the positive region is over the phenyl ring and NH group.

Synthesis of Novel 2-(Substituted amino)alkylthiopyrimidin-4(3H)-ones as Potential Antimicrobial Agents

5-Alkyl-6-(substituted benzyl)-2-thiouracils 3a,c were reacted with (2-chloroethyl) diethylamine hydrochloride to afford the corresponding 2-(2-diethylamino)ethylthiopyrimidin-4(3H)-ones 4a,b. Reaction of 3a–c with N-(2-chloroethyl)pyrrolidine hydrochloride and/or N-(2-chloroethyl)piperidine hydrochloride gave the corresponding 2-[2-(pyrrolidin-1-yl)ethyl]-thiopyrimidin-4(3H)-ones 5a–c and 2-[2-(piperidin-1-yl)ethyl]thiopyrimidin-4(3H)-ones 6a,b, respectively. Treatment of 3a–d with N-(2-chloroethyl)morpholine hydrochloride under the same reaction conditions formed the corresponding 2-[2-(morpholin-4-yl)ethyl]thiopyrimidines 6c–f. On the other hand, 3a,b were reacted with N-(2-bromoethyl)phthalimide and/or N-(3-bromopropyl)phthalimide to furnish the corresponding 2-[2-(N-phthalimido)ethyl]-pyrimidines 7a,b and 2-[3-(N-phthalimido)-propyl]pyrimidines 7c,d, respectively. Compounds 3a–d, 4a,b, 5a–c, 6a–f and 7a–d were screened against Gram-positive bacteria (Staphylococcus aureus ATCC 29213, Bacillus subtilis NRRL 4219 and Bacillus cereus), yeast-like pathogenic fungus (Candida albicans ATCC 10231) and a fungus (Aspergillusniger NRRL 599). The best antibacterial activity was displayed by compounds 3a, 3b, 4a, 5a, 5b, 6d, 6f, 7b and 7d, whereas compounds 4b, 5b, 5c, 6a, 6b and 6f exhibited the best antifungal activity.