Purine Nucleoside Analogs. 12. Synthesis of Novel 8,9-Disubstituted Guanine Derivatives by S-Alkylation of 2-Acetamido-9-(2-acetoxyethoxymethyl)-6-oxo-8-thioxopurine

S-Alkylation of 2-acetamido-9-(2-acetoxyethoxymethyl)-6-oxo-8-thioxopurine was used to synthesize its novel S- and N₍₇₎-substituted derivatives. We have established the effect of the structure of the alkylating agent on the reaction conditions and its regioselectivity. We have shown that the synthesized guanine derivatives can be modified further.     

Selective S-methylation of highly fluorinated thiocarbamates

A series of new S-methyl O-fluoroalkyl N-alkyl(aryl)imidothiocarbonates were prepared by S-methylation of various fluoroalkylated thiocarbamates with methyl iodide in the presence of cesium carbonate and tetrabutylammonium iodide (TBAI) in tetrahydrofuran (THF) at room temperature. As expected from the mostly soft electrophilic alkyl halide (MeI), no isomer products derived from N-methylation were detected. The products were characterized by spectroscopic (¹H, ¹³C and ¹⁹F) NMR, infrared, and high-resolution mass spectrometric techniques.     

New sulfonated engineering polymers via the metalation route. II. Sulfinated/sulfonated poly(ether sulfone) PSU Udel and its crosslinking

New mixed sulfinated/sulfonated polysulfone PSU Udel has been produced by partial oxidation of sulfinated PSU with NaOCl. From the mixed sulfinated/sulfonated PSU, thin crosslinked polymer films have been produced by S-alkylation of the residual sulfinate groups with α,ω-diiodoalkanes having 4–10  (CH₂) units. The advantages of the partial oxidation process using NaOCl are as follows: (1) The desired oxidation degree can be adjusted finely. (2) No side reactions take place during oxidation. (3) The partially oxidized polymers is stable at ambient temperature. By variation of the oxidation degree of the sulfinated/sulfonated prepolymer and by variation of the chain length of the diiodo crosslinker, crosslinked membranes with a large range of properties in terms of ionic conductivity, swelling, and permselectivity have been produced. The partially oxidized polymers have been characterized by redox titration, ¹H-NMR, and FTIR. The crosslinked membranes have been characterized in terms of ionic conductivity (resistance), permselectivity, and swelling in dependence on ion-exchange capacity and oxidation degree of the prepolymers. In addition, the thermal stabilities of the membranes have been determined by TGA, and FTIR spectra have been recorded on the crosslinked films. Selected membranes show low ionic resistances, low swelling, and good temperature stability which makes them promising candidates for application in (electro)membrane processes. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1441–1448, 1998     

Synthesis and Reactivity of Mannich Bases. XVIII. Reaction of Dithiocarbamic Acid Salts With Mannich Bases Derived from Ortho-Hydroxyacetophenones

The reaction of Mannich bases derived from ortho-hydroxyacetophenones with N,N-dialkyldithiocarbamic acid salts result in the formation of the corresponding dithiocarbamic acid esters via an amine moiety replacement when the process is conducted in cold water. Attempts to carry out the synthesis in refluxing ethanol-water mixture led to the insertion of carbon sulfide at the C—N bond in Mannich bases. N-Aryldithiocarbamic acid salts afforded on reaction with the above-mentioned Mannich bases only bis-(2-(2-hydroxybenzoyl)ethyl)thioethers.     

A Cs2CO3-mediated simple and selective method for the alkylation and acylation of 3,4-dihydropyrimidin-2(1H)-thiones

Alkyl and acyl derivatives of 3,4-dihydropyrimidin-2(1H)-thiones were synthesized in good to excellent yields in the presence of Cs₂CO₃, a mild base. The method evidences a selective S-alkylation when using acyl chlorides as efficient acylating agents at room temperature on the 2-thioxo-dihydropyrimidone moiety. A possible mechanistic interpretation of the different selectivities in case of alkylation and acylation was done with the help of a geometry optimization process.     

Synthesis and Reactions of Novel 2,5-Disubstituted 1,3,4-Thiadiazoles

The desired 1,3,4-thiadiazole compounds bearing different substituents were obtained by the cyclization of the corresponding thiosemicarbazide followed by the reaction with electrophilic reagents, such as aromatic aldehydes, isatin, phenyl isothiocyanate, and carbon disulfide. The newly synthesized 2,5-disubstituted 1,3,4-thiadiazoles were obtained in good yields and their structures were elucidated by spectral data and elemental analysis.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Novel 3-Cyanosubstituted 1,2-Thiaphosphacyclanes: Synthesis and Stereochemistry

The facile synthetic route to 5- and 6-membered 3-cyano-2-oxo-1,2-thiaphosphacyclanes and 6-cyano-2-oxa-10-oxa(thia)-phosphabicyclo [4.4.0]-decane-1-oxides was elaborated via intramolecular S-alkylation in a series of y -haloalkylsubstituted thiophosphorylacetonitriles. The compounds were used to prepare novel P(III)-containing bidentate ligands with definite stereochemistry. Diastereomeric transformations among 2-oxo-1,2-thiaphosphinanes were found and the mechanism of such transformations is suggested.     

含氮或碳中心原子的窝穴体开链类似物的合成与研究

本文合成了十种含氮或碳中心原子的窝穴体开链类似物(1a～e, 2a～e). 通过三乙醇胺, 季戊四醇及4-羟基安替比林的O-烷基化和用季戊四溴对2-巯基苯并咪唑, 2-巯基苯并噻唑的S-烷基化方法. 以它们作为液膜(CHCl~3)离子载体对Ag(I)迁移实验表明, 化合物1a～e迁移能力较强.     

Reaction of diketene with cyanothioacetamide: A convenient and regioselective method for the preparation of new 4(1H)-pyridone derivatives

The reaction of diketene with cyanothioacetamide in dry dioxane in the presence of triethylamine gives triethylammonium 3-cyano-6-methyl-4-oxo-1,4-dihydro-2-pyridinethiolate. The regioselective S-alkylation of this thiolate is a convenient method for the preparation of substituted 4(1H)-pyridones and also derivatives of thiazolo[3,2-a]pyridine and thieno[2,3-b]pyridine. The action of 2-amino-1,1,3-tricyanopropene on this thiolate leads to its transformation into a new heterocyclic system, namely, 5H-pyrido[2′,3′:4,5]thiopyrano[2,3-b]pyridine; treatment with iodine yields the oxidation product, namely, the corresponding bis(2-pyridyl) disulfide. The structure of isopropyl (3-cyano-6-methyl-4-oxo-1,4-dihydro-2-pyridinyl)thioacetate was confirmed by X-ray diffraction structural analysis. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 716–725, May, 2007.