Elie Abushanab

Practical enantiospecific syntheses of (+) erythro-9- (2s-hydroxy-3r-nonyl) adenine.☆

Abstract Three enantiospecific syntheses of 1S (2S-benzyloxethyl) oxirane (9) from L-ascorbic acid, L(+) tartaric acid, and Z-butene 1,4-diol are reported. The conversion of 9 to 2S-hydroxy-3R-nonylamine (19) is also described.

A facile synthesis of β- and γ- hydroxyphosphonate esters from epoxides

Abstract A BF3.OEt2 catalyzed, regiospecific nucleophilic ring opening reaction of epoxides by dialkyl phosphite and methanephosphonate esters is described. The reaction proceeds in good to excellent yields to give the title compounds and is compatible with a variety of other functional groups.

Synthesis of Chiral 1′,2′-SECO-Nucleosides OF Guanine AND Uracil

Abstract 2R-Chloromethoxy-1, 3S-dibenzyloxybutane (6a) and 2R-chloro methoxy-1, 3S,4-tribenzyloxybutane (6b) chirons readily available from D-isoascorbic acid, were used in the preparation of 1′,2′-seco-nucleo-sides of uracil and guanine.

Phosphonate isosteres of phospholipids

Abstract A facile synthesis of phosphonolipid isosteres of the platelet activating factor(PAF) and the anticancer ether lipid ET-O-18 is described.

The Chemistry of L-Ascorbic and D-Isoascorbic Acids. 3: Efficient Syntheses of Pure R- and S- 1,2-O-Isopropylidene-1,2,4-Butanetriols1

Abstract Both enantiomers of 1,2-0-isopropylidene-1,2,4-butanetriol were prepared by two different and simple methods starting from readily available L-ascorbic and D-isoascorbic acids.

A stereospecific synthesis of pyrimidine β-D-2'-deoxyribonucleosides

Abstract A stereospecific route for the synthesis of pyrimidine 2′-β-D-deoxyribonucleosides has been developed using suitably modified methyl 2-deoxy-D-ribofuranosides. The stereochemistry of the nucleoside bond is dictated by the chirality at C-4 of the pentofuranose. A novel palladium hydroxide catalyzed alcholysis of a nucleoside bond has been discovered. Preliminary studies of the mechanism and limitations of this reaction are described.

The “β-Fluorine Effect” in the Non-Metal Hydride Radical Deoxygenation of Fluorine-Containing Nucleoside Xanthates

Abstract An alternative method to conduct a Barton-McCombie deoxygenation in nucleosides is described. The utility of the procedure is limited to structures with an electronegative substituent, particularly fluorine, in the β-position relative to the radical center. The process is radical in nature and triggered by peroxides. The abstraction of hydrogen from the solvent is favorably influenced by the presence of a β-fluorine.

UNPRECEDENTED CHLORINATION OF 2,2'-ANHYDRO-5,6-DIHYDROPYRIMIDINE NUCLEOSIDES DURING DDQ OXIDATION

Abstract Chloride ion, derived from 2,3-dichloro-5,6-dicyanohydroquinone (DDHQ), was found to participate in opening of the 2,2′-anhydro bond of 5,6-dihydropyrimidine nucleosides, but not their 5,6-unsaturated counterparts. The increased basicity of the nucleosidic nitrogen is believed to be a factor in this unprecedented reaction.

A practical and stereospecific approach to the synthesis of 3'-deoxy-2',3'-didehydrothymidine (D4T)

Abstract Starting with D-glucose, 5-t-butyldimethylsilyl-3-deoxy-D-arabinose (5) was prepared. Condensation of 5 with cyanamide followed by reaction of the resulting oxazoline 6 with methyl-2-formylpropionate furnished the anhydronucleoside 7. t-Butoxide elimination of 7 gave the target compound in moderate yields due to concomitant 1′,2′-double bond formation. However, phenylselenolate and phenylthiolate opened 7 regiospecifically to the corresponding seleno and thio compounds, 10 and 11, respectively. Oxidative elimination of 10 and the pivaloyl derivative 12 gave 5′-t-butyldimethylsilyl (8) and 5′-pivaloyl (13) D4T in excellent yield.

Synthesis of substituted 4H-thieno[2,3-b][1]benzothiopyran-4-ones as possible schistosomicidal agents@@@Synthese von substituierten 4H-Thieno[2,3-b][1]benzothiopyran-4-onen als mgliche schistosomicide Wirkstoffe

SummaryInteraction of ethyl 2-acetamido-5-bromothiazole-4-carboxylate (2) with 2-methyl-5-chlorothiophenol (3) afforded the thioether4, which was hydrolysed to the corresponding carboxylic acid5. Attempted cyclization of5 to6 yielded the decarboxylated product7. On the other hand, interaction of 2-acetamido-5-bromothiazole (9) with thiosalicylic acid (10) yielded the thioether11, which was cyclized to compound12. Acid hydrolysis of12 yielded the amino derivative13, which was reacted with certain selected alkyl halides using sodium hydride to afford compounds14–18.ZusammenfassungDie Reaktion von Ethyl 2-Acetamido-5-bromthiazol-4-carboxylat (2) mit 2-Methyl-5-chlorthiophenol (3) ergab den Thioether4, der zur entsprechenden Carbonsäure5 hydrolysiert wurde. Die versuchte Cyclisierung von5 zu6 ergab das Decarboxylierungsprodukt7. Andererseits ergab die Reaktion von 2-Acetamido-5-bromthiazol (9) mit Thiosalizylsäure (10) den Thioether11, der zu Verbindung12 cyclisiert werden konnte. Saure Hydrolyse von12 ergab das Aminoderivat13, das mit geeigneten Alkylhalogeniden unter Verwendung von Natriumhydrid zu den Verbindungen14–18 führte.SummaryA new series of thiophenic isosters of thioxanthones, namely: 2-substituted-4H-thieno[2,3-b][1]benzothiopyran-4-ones and 5-substituted-2-nitro-8-methyl-4H-thieno[2,3-b][1]benzothiopyran-4-ones were synthesized as potential schistosomicidal agents. The synthesized compounds were characterized by their1H-NMR data.ZusammenfassungEs wurde eine neue Serie von thiophenischen Isosteren des Thioxanthons, nämlich 2-substituierte 4H-Thieno[2,3-b][1]benzothiopyran-4-one und 5-substituierte 2-Nitro-8-methyl-4H-thieno[2,3-b][1]benzothiopyran-4-one als potentielle schistosomicide Wirkstoffe synthetisiert. Die synthetisierten Verbindungen wurden mittels ihrer1H-NMR Daten charakterisiert.