Ahmed H. Moustafa

Synthesis and Analgesic Activity of Some New Pyrazoles and Triazoles Bearing a 6,8-Dibromo-2-methylquinazoline Moiety

2-(6,8-Dibromo-2-methylquinazolin-4-yloxy)-acetohydrazide (4) was prepared by the reaction of 6,8-dibromo-2-methylbenzo-[d][1,3]oxazin-4-one with formamide to afford quinazolinone 2, followed by alkylation with ethyl chloroacetate to give the ester 3. Treatment of ester 3 with hydrazine hydrate and benzaldehyde afforded 4 and styryl quinazoline 5. The hydrazide was reacted with triethyl orthoformate, acetylacetone and ethyl acetoacetate and benzaldehyde derivatives to afford the corresponding pyrazoles 6, 7, 9 and hydrazone derivatives 10a-c. Cyclization of hydrazones 10a-c with thioglycolic acid afforded the thiazole derivatives 11a-c. Reaction of the hydrazide with isothiocyanate derivatives afforded hydrazinecarbothioamide derivatives 12a-c, which cyclized to triazole-3-thiols and thiadiazoles 13a-c and 14a-c, respectively. Fusion of the hydrazide with phthalimide afforded the annelated compound 1,2,4-triazolo[3,4-a]isoindol-5-one (15). The newly synthesized compounds were characterized by their spectral (IR, 1H-, 13C-NMR) data. Selected compounds were screened for analgesic activity.

Synthesis of Some New Pyrimidine Derivatives of Expected Antimicrobial Activity

2-(2-Arylvinyl)-6-methyl-4-mercapto-5-acetylpyrimidine derivatives 3 a − d , were synthesized form the reaction of the appropriate isothiocyanate derivatives 1 with α, β -unsaturated aminoketone 2 . Compound 3 was alkylated with methyl iodide, ethyl chloroacetate and/or bromosugar to afford 6 , 9 , and 22 a − c respectively. Cyanoethylation of 3 b afforded 6 b which upon cyclization with hydrazine hydrate gave pyrazolopyrimidine 7 . Bromination of 6 b gave dibromo compound 8 . Thieno[2,3-d]pyrimidines 10 and 12 were obtained by ring closure of the alkylated product 9 with TEA/EtOH and/or through cyclization of the hydrazide 11 with NaOEt/EtOH. While, Thieno[2,3-d]pyrimidine 14 was obtained directly by alkylation of 3 b with chloroacetone in both TEA/EtOH and Na2CO3 solution. The cycloaddition products 15 and 16 were obtained by reaction of 3b with diethylmaleate and/or maleic anhydride. Formation of 1,3,4-oxadiazole 17 , pyrazoles 18 and 19 where obtained by treating the hydrazide 11 with carbon disulphide, triethyl orthoformate and acetylacetone respectively. While, reaction of 11 with p-chlorobenzaldehyde resulted in the Schiffs base 20 which, cyclizes with thioglycolic acid to afford thiazolidone 21 . Hydrolysis of 22 a − c in TEA/MeOH afforded the free sugar 23 a − c . The structures of all the new compounds were confirmed using IR, 1 H, and 13 C NMR spectra and microanalysis. Selected members of the synthesized compound were screened for antimicrobial activity.

Synthesis and anticancer activity of some new s-glycosyl and s-alkyl 1,2,4-triazinone derivatives.

A series of S-glycosyl and S-alkyl derivatives of 4-amino-3-mercapto-6-(2-(2-thienyl)vinyl)-1,2,4-triazin-5(4H)-one (1)were synthesized using different halo compounds such as preacetylated sugar bromide, 4-bromobutylacetate, 2-acetoxyethoxy-methyl bromide, 3-chloropropanol, 1,3-dichloro-2-propanol, epichlorohydrin, allyl bromide, propargyl bromide, phthalic and succinic acids in POCl3. The structures of the synthesized compounds have been deduced from their elemental analysis and spectral (IR, 1H-NMR, and 13C-NMR) data. Some of the synthesized compounds were screened as anticancer agents. Significant anticancer activities were observed in vitro for some members of the series, and compounds 4-Amino-3-(3-hydroxypropylthio)-6-(2-(2-thienyl)vinyl)-1,2,4-triazin-5(4H)-one (12) and 3-(4-Oxo-3-(2-(2-thienyl)vinyl)-4H-[1,3,4]thiadiazolo-[2,3-c][1,2,4]tr-iazin-7-yl)propanoic acid (18) are active cytotoxic agents against different cancer cell lines.

Synthesis and Evaluation of Antimicrobial Activity of Some Pyrimidine Glycosides

Reaction of ethyl 4-thioxo-3,4-dihydropyrimidine-5-carboxylate derivatives 1a,b and ethyl 4-oxo-3,4-dihydropyrimidine-5-carboxylate 1c with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide in KOH or TEA afforded ethyl 2-aryl-4-(2′,3′,4′,6′-tetra-O-acetyl-β-D-glucopyranosylthio or/ oxy)-6-methylpyrimidine-5-carboxylate 6a-c. The glucosides 6a and 6b were obtained by the reaction of 1a and 1b with peracetylated glucose3 under MW irradiation. Mercuration of 1a followed by reaction with acetobromoglucose gave the same product 6a. The reaction of 1a-c with peracetylated ribose 4 under MW irradiation gave ethyl 2-aryl-4-(2′,3′,5′-tri-O-acetyl-β-D-ribofuranosylthio)-6-methylpyrimidine-5-carboxylate 8a–c. The deprotection of 6a–c and 8a–c in the presence of methanol and TEA/H2O afforded the deprotected products 7a–c and 9a–c. The structure were confirmed by using 1H and 13CNMR spectra. Selected members of these compounds were screened for antimicrobial activity.

Synthesis and antibacterial activity of some glucosyl- and ribosyl-pyridazin-3-ones.

Reaction of 5,6-diphenylpyridazin-3(2H)-one 1a,b with 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl bromide 2 in K2CO3/acetone gave 5,6-diphenyl-N2-(2′,3′,4′,6′-tetra-O-acetyl-β-D-glucopyranosyl)pyridazin-3-one 5a,b. The same nucleosides 5a,b were obtained by reaction of 1a,b with peracetylated glucose 3 under MW irradiation. Mercuration of 1a,b followed by reaction with glucosyl bromide 2 gave the same nucleosides 5a,b. The riboside 4-cyano-5,6-diphenyl-N2-(2′,3′,5′-tri-O-acetyl-β-D-ribofuranosyl)-pyridazin-3-one 8 was obtained by reaction of 4-cyanopyridazinone 1b with peracetylated ribose 7 under MW irradiation. The deprotected nucleosides 6a,b and 9 were obtained by stirring of 5a,b and 8 in methanol and TEA/H2O. The structure was confirmed using 1H and 13C-NMR spectra. Selected members of these compounds were screened for antibacterial activity.

Synthesis of Acyclovir and HBG Analogues Having Nicotinonitrile and Its 2-methyloxy 1,2,3-triazole

Reaction of pyridin-2(1H)-one 1 with 4-bromobutylacetate (2), (2-acetoxyethoxy)methyl bromide (3) gave the corresponding nicotinonitrile O-acyclonucleosides, 4 and 5, respectively. Deacetylation of 4 and 5 gave the corresponding deprotected acyclonucleosides 6 and 7, respectively. Treatment of pyridin-2(1H)-one 1 with 1,3-dichloropropan-2-ol (8), epichlorohydrin (10) and allyl bromide (12) gave the corresponding nicotinonitrile O-acyclonucleosides 9, 11, and 13, respectively. Furthermore, reaction of pyridin-2(1H)-one 1 with the propargyl bromide (14) gave the corresponding 2-O-propargyl derivative 15, which was reacted via [3+2] cycloaddition with 4-azidobutyl acetate (16) and [(2-acetoxyethoxy)methyl]azide (17) to give the corresponding 1,2,3-triazole derivatives 18 and 19, respectively. The structures of the new synthesized compounds were characterized by using IR, 1H, 13C NMR spectra, and microanalysis. Selected members of these compounds were screened for antibacterial activity.

Double-headed acyclo C-nucleoside analogues. Functionalized 1,2-bis-(1,2,4-triazol-3-yl)ethane-1,2-diol.

Reaction of L-tartaric acid with thiocarbohydrazide afforded (1R, 2S)-1,2-bis(4-amino-5-mercapto-1,2,4-triazol-3-yl)-ethane-1,2-diol (3). The functional groups in 3 allowed the construction of fused heterocycles on the 1,2,4-triazole rings, mainly of the 1,2,4-triazolo[3,4-b][1,3,4]thiadiazine type as in 4, 5, 7, 10, 13 and 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole type as in 14.

Synthesis and antimicrobial evaluation of novel pyrazolones and pyrazolone nucleosides.

The synthesis of a novel series of 4-arylhydrazono-5-methyl-1,2-dihydropyrazol-3-ones 4a–h, and their N 2-alkyl and acyclo, glucopyranosyl, and ribofuranosyl derivatives is described. K2CO3 catalyzed alkylation of 4a–h with allyl bromide, propargyl bromide, 4-bromobutyl acetate, 2-acetoxyethoxymethyl bromide, and 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide proceeded selectively at the N 2-position of the pyrazolinone ring. Glycosylation of 4a with 1,2,3,5-tetra-O-acetyl-β-D-ribofuranose under Vorbruggen glycosylation conditions gave the corresponding N 2-4-arylhydrazonopyrazolone ribofuranoside 9a in good yield. Conventional deprotection of the acetyl protected nucleosides furnished the corresponding 4-arylhydrazonopyrazolone nucleosides in good yields. Selected numbers of the newly synthesized compounds were screened for antimicrobial activity. Compounds 4b, 12a, and 14d showed moderate activities against Aspergillus flavus, Penicillium sp., and Escherichia coli.

Synthesis and Antimicrobial Activity of Some S-β-D-Glucosides of 4-Mercaptopyrimidine

5-Acetyl-2-aryl-6-methyl-4-(2,3,4,6-tetra- O -acetyl-β-D-glucopyranosylmercapto)pyramidines 3a–c were obtained by the reaction of 5-acetyl-2-aryl-6-methyl-pyrimidine thiol 1a–c with 2,3,4,6-tetra- O -acetyl-α-D-glucopyranosyl bromide (2) in aq. KOH/acetone. The reaction of 1a–c with peracetylated galactose 5 and peracetylated ribose 8 under MW irradiation gave 5-acetyl-2-aryl-6-methyl-4-(2,3,4,6-tetra- O -acetyl-β-D-galactopyranosylmercapto)pyrimidine 6a–c and 5-acetyl-2-aryl-6-methyl-4-(2,3,5-tri- O -acetyl-β-D-ribofuranosylmercapto)pyrimidines 9a–c. The deprotection of 3a–c, 6a–c, and 9a–c in the presence of methanol and TEA/H2O yielded the deprotected products 4a–c, 7a–c, and 10a–c. The structures of the compounds were confirmed by using IR, 1H, 13C spectra and microanalysis. Selected members of these compounds were screened for antimicrobial activity.

The Synthesis of Triazolothiadiazines and Thiadiazoles From 1,2-Bis-(4-amino-5-mercapto-1,2,4-triazol-3-yl)- Ethanol and Ethane

The reaction of DL-malic and succinic acids with thiocarbohydrazide afforded 1,2-bis[4-amino-5-mercapto-1,2,4-triazol-3-yl]-ethane derivatives 3a and 3b. The reaction of 3a,b with phenacyl bromide and benzoin afforded 1,2-bis-1,2,4-triazolo [3,4-b][1,3,4]thiadiazine derivatives 4 and 5. The carboethoxymethylation of 3a and 3b gave 6a and 6b, respectively, and their reactions with carbon disulfide and benzoylisothiocyanate gave the 1,2-bis-1,2,4-triazolo[3,4-b][1,3,4]thiadiazole 7 and 9, and with p-nitrobenzaldehyde gave a Schiffs base and dihydrothiadiazole 8. The structures were confirmed by using 1 H and 13 C NMR spectra. Selected members of these compounds were screened for antimicrobial activity.