Anhydrous Potassium Carbonate Research Articles

Regioselective N- and O-Alkylation of 3H-[1,2,3]triazolo[4,5-d]pyrimidine-5,7(4H,6H)-diones (8-Azaxanthines) and Transformation of 3-Alkyl Derivatives into 1-Alkyl Isomers

The alkylation on the pyrimidine ring of 3-methyl-3H-[1,2,3]triazolo]4,5-d]pyrimidine-5,7(4H,6H)-diones (1) with an equimolecular amount of alkylating agent in the presence of anhydrous potassium carbonate in aprotic solvents under heating took place only at the 4-position. The similar alkylation on the triazole ring of 6-methyl-1H-[1,2,3]triazolo[4,5-d]pyrimidine-5,7(4H,6H)-diones (4) with an equivalent alkylating reagent happened simultaneously at the 1- and 2-positions with the priority at the 2-position. On the other hand, the alkylation of 3,6-disubstituted derivatives (12a-d) at room temperature led to the 5-0-alkylation (14a-e) accompanied with the 4-N-alkylation (3a, 13a-d), but at high temperature only the 4-N-alkylation occurred. The 3,4,6-tri-substituted derivatives (3a, 13d) underwent transformation with excess alkylating agents at high temperature leading to the formation of 1,4,6-trisubstituted derivatives (7, 15) with elimination of the 3-substituent in the same manner as xanthine.

Sulfonated copoly(phthalazinone ether ketone nitrile)s as proton exchange membrane materials

Sulfonated poly(phthalazinone ether ketone nitrile) copolymers (SPPEKN) were prepared by copolymerization of disodium 3,3′-disulfonate-4,4′-difluorobenzophenone (SDFB-Na), 2,6-difluorobenzonitrile (2,6-DFBN), and 4-(4-hydroxyphenyl)-1(2 H)-phthalazinone (DHPZ) at 160 °C in N-methyl-2-pyrrolidione containing anhydrous potassium carbonate. The polymerization reactions proceeded smoothly and in high yield giving high molecular weight SPPEKN copolymers with different sulfonic acid content (SC) values. The polymer structures were defined by 1H NMR and FT-IR. Membrane films of SPPEKN copolymers in both salt and acid forms, prepared at SDFB-Na to 2,6-DFBN feed ratios up to 60/40 mol/mol, were cast from the N, N-dimethylacetamide (DMAc) polymer solutions. The presence of highly polar nitrile groups are expected to increase inter-chain molecular forces, contributing to the observed reduction in water swelling over previously prepared sulfonated poly(phthalazinone ether ketone) (SPPEK) copolymers. Membranes containing nitrile groups are expected to show improved adhesion between polymer and catalyst when utilized in a fuel cell. All SPPEKN copolymers exhibited tensile strength higher than that of Nafion ®117. The proton conductivities of acid form SPPEKN copolymers (SPPEKNH)s, prepared at the sulfonated/unsulfonated monomer feed ratio above 0.35 mol/mol, were around 10 −1 S/cm at 80 °C, which is close to or higher than that of Nafion ®117 under same measurement conditions.

A Synthesis of Heteroaromatic S- and N-β-Glycosides of N-Acetylglucosamine under Phase-Transfer Conditions

The use of crown ethers for a phase transfer-catalyzed synthesis of heteroaromatic glycosides of N-acetylglucosamine was studied. The solid-liquid system and the catalysis by 15-crown-5 were found to provide for both a 100% conversion of the alpha-D-glucosaminyl chloride peracetate and a high reaction rate. The interaction of alpha-D-glucosaminyl chloride peracetate and oxadiazole and triazole mercapto derivatives capable of thiol-thione tautomerism carried out at room temperature in acetonitrile in the presence of anhydrous potassium carbonate and crown ethers was shown to lead to both S- and N-glycosides. The structures of the compounds synthesized were confirmed by X-ray analysis and 13C and 1H NMR spectroscopy.

Synthesis and Properties of First Bis(fluoreno)crownophanes.

Alkylation of 2,7-dihydroxy-9H-fluoren-9-one with 2-(2-chloroethoxy)ethanol, 2-[2-(2-chloroethoxy)-ethoxy]ethanol, and 2-{2-[2-(2-chloroethoxy)ethoxy]ethoxy}ethanol in dimethylformamide in the presence of potassium carbonate gave 78–80% of the corresponding diols which were treated with p-toluenesulfonyl chloride in a dioxanechloroform mixture in the presence of triethylamine at 0– 5°C (30 h). The resulting bis(p-toluene-sulfonates) were brought into condensation with 2,7-dihydroxy-9H-fluoren-9-one in a very dilute solution in dimethylformamide containing anhydrous potassium carbonate at 80–85°C. Appropriate treatment of the reaction mixture, followed by chromatographic purification afforded 53–27% of the first representatives of a new class of cyclophanes, bis(oxofluoreno)crownophanes. Raising the temperature to 95–105°C resulted in an appreciable decrease of the product yield. The yield of the target products did not increase on replacement of potassium carbonate by cesium carbonate.

Synthesis of Alkyl‐, Aryl‐ and Heteroaryl‐Substituted 2‐[3‐Oxo‐2,3‐dihydro‐1H‐pyrazol‐2‐yl]‐6(4)‐trifluoromethylpyrimidines from β‐Alkoxyvinyl Trifluoromethyl Ketones.

A general method for the synthesis of a novel series of 4-alkyl, 4-aryl, and 4-heteroaryl-substituted 2-[4-(2-hydroxyethyl)-5-methyl-3-oxo-2,3-dihydro- 1H-pyrazol-2-yl]-6(4)-trifluoromethylpyrimidines, in 35-80% yields, by cyclocondensation of 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones with 1-amidino-4-(2-hydroxyethyl)-3-methyl-3-pyrazolin-5-one in the presence of anhydrous potassium carbonate, is described.

Novel and Convenient One‐Pot Synthesis of 3‐Aroyl‐7‐hydroxy‐6‐nitroflavones.

Abstract A novel and conveient one‐pot synthesis of 3‐aroyl‐7‐hydroxy‐6‐nitroflavones from 2′,4′‐dihydroxy‐5′‐nitroacetophenone and (substituted)benzoyl chlorides in refluxing dry acetone in the presence of anhydrous potassium carbonate was developed. The structures of the prepared compounds were characterized by IR, 1H NMR, and MS spectroscopy.

Preparation and Characterization of Fluorine-containing Aromatic Condensation Polymers VIII. Aromatic Polyether and Copolyethers from 2,2-Bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-Bis(4-hydroxyphenyl)propane, or both and Bis(4-fluorophenyl)phenylphosphine Oxide

A series of hexafluoroisopropylidene group-containing aromatic polyether and copolyethers with a wide range of unit ratios were synthesized by high-temperature solution polycondensation of 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane (1a), 2,2-bis(4-hydroxyphenyl)propane (1b), or both with bis(4-fluorophenyl)phenylphosphine oxide, and the effect of fluorine substitution on the properties of these polymers is discussed in relation to the fluorine contents. High- to moderate-molecular-weight polyethers with reduced viscosities of 0.39–0.55 dL g−1 were obtained in high yields by using anhydrous potassium carbonate as a base and N,N-dimethylacetamide as a medium at 160 °C for 48 h. Regardless of the fluorine contents, these polymers all were soluble in various organic solvents, including benzene, chloroform, and tetrahydrofuran, and afforded colorless, transparent, and tough films by solution casting. The contact angles of the films to water increased significantly with increasing fluorine content. The glass transition temperatures also increased monotonously with the increase of fluorine content, whereas the temperatures of 5% weight loss and 10% weight loss under nitrogen were scarcely affected by fluorine substitution. These films with and without fluorine exhibited a very sharp cutoff at a wavelength shorter than 290 nm and are colorless. Optically estimated dielectric constant of 1a-based homopolyether was 2.79, which was remarkably lower than the value of 1b-based homopolyether, 2.97.

Synthesis of Alkyl-, Aryl- and Heteroaryl-Substituted 2-[3-Oxo-2,3-dihydro-1H-pyrazol-2-yl]-6(4)-trifluoromethylpyrimidines from β-Alkoxyvinyl Trifluoromethyl Ketones

A general method for the synthesis of a novel series of 4-alkyl, 4-aryl, and 4-heteroaryl-substituted 2-[4-(2-hydroxyethyl)-5-methyl-3-oxo-2,3-dihydro- 1H-pyrazol-2-yl]-6(4)-trifluoromethylpyrimidines, in 35-80% yields, by cyclocondensation of 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones with 1-amidino-4-(2-hydroxyethyl)-3-methyl-3-pyrazolin-5-one in the presence of anhydrous potassium carbonate, is described.

Synthesis and Properties of First Bis(fluoreno)crownophanes

Alkylation of 2,7-dihydroxy-9H-fluoren-9-one with 2-(2-chloroethoxy)ethanol, 2-[2-(2-chloroethoxy)-ethoxy]ethanol, and 2-{2-[2-(2-chloroethoxy)ethoxy]ethoxy}ethanol in dimethylformamide in the presence of potassium carbonate gave 78–80% of the corresponding diols which were treated with p-toluenesulfonyl chloride in a dioxanechloroform mixture in the presence of triethylamine at 0– 5°C (30 h). The resulting bis(p-toluene-sulfonates) were brought into condensation with 2,7-dihydroxy-9H-fluoren-9-one in a very dilute solution in dimethylformamide containing anhydrous potassium carbonate at 80–85°C. Appropriate treatment of the reaction mixture, followed by chromatographic purification afforded 53–27% of the first representatives of a new class of cyclophanes, bis(oxofluoreno)crownophanes. Raising the temperature to 95–105°C resulted in an appreciable decrease of the product yield. The yield of the target products did not increase on replacement of potassium carbonate by cesium carbonate.

A stereochemical investigation of the nucleophilic addition of methyl ethyl ketone to (E)-alkyloxindolylideneacetates

The reaction of (E)-(2-oxo-1,2-dihydroindol-3-ylidene)acetic acid esters (1) with methyl ethyl ketone in the presence of morpholine as a catalyst gave 4-oxo-2-(2-oxo-2,3-dihydro-1H-indole-3-yl)hexanoic acid esters, a diastereomeric mixture of two isomers (2A and 2B). Using aluminium oxide as a catalyst for the above reaction led to the formation of 4-oxo-3-methyl-2-(2-oxo-2,3-dihydro–1H-indole-3-yl)-pentanoic acid esters as a mixture of three isomers 3A, 3B and 3C, which upon methylation with methyl iodide in acetone and in the presence of anhydrous potassium carbonate yield the corresponding methylated products. The structural assignments of the new compounds are based on their chemical and spectroscopic properties. The stereochemical structures of 5aA, 5bB and 5aC are identified by X-ray analysis.

Reaction of Malonic Acid Derivatives with Acetylenic Diphosphonates

The primary addition products in the reactions of malonic esters, cyanoacetic esters, and malononitrile with acetylenediphosphonates in acetonitrile in the presence of anhydrous potassium carbonate are potassium derivatives, viz. esters and nitriles of the corresponding 2-alkoxycarbonyl(or 2-cyano) -3,4-bis(di-alkoxyphosphinoyl)-2-potassiobut-3-enoic acid. Further hydrogen replacement for potassium in the nitriles is accompanied by isomerization involving double-bond shift and geometry change. (E)- and (Z)-3,4-bis(dial-koxyphosphinoyl)-2-cyano-2-potassiobut-3-enenitriles (the alkoxy groups are CH3O and C2H5O) are crystalline compounds; they were isolated and characterized.

Novel and Convenient One‐Pot Synthesis of 3‐Aroyl‐7‐Hydroxy‐6‐Nitroflavones

A novel and conveient one‐pot synthesis of 3‐aroyl‐7‐hydroxy‐6‐nitroflavones from 2′,4′‐dihydroxy‐5′‐nitroacetophenone and (substituted)benzoyl chlorides in refluxing dry acetone in the presence of anhydrous potassium carbonate was developed. The structures of the prepared compounds were characterized by IR, 1H NMR, and MS spectroscopy.

Synthesis of polystyrene‐supported glucosamine resin and its adsorption properties for metal ions

AbstractA novel chelating resin polystyrene‐supported glucosamine was prepared by the reaction of chloromethylated polystyrene with glucosamine hydrochlorate, using anhydrous potassium carbonate as catalyst and dimethylformamide as solvent. Infrared spectra and elementary analysis were used to confirm its structure. The adsorption of the resin for Cu2+, Ni2+, Hg2+, Co2+, Cd2+, and Pb2+ was investigated, as well as various factors affecting the adsorption such as time, temperature, ion concentration, and pH. The results showed that the resin had good adsorption capacities for Cu2+, Ni2+, and Hg2+. The adsorption was controlled by liquid film diffusion and adsorption isothermal data could be well interpreted by the Freundlich equation. Values of adsorption activation energy and adsorption Gibbs free energy were calculated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 890–896, 2005

Unusual Reduction of a Lactone Carbonyl in a Bu3SnCl and Na(CN)BH3 Mediated Radical Cyclization of 3‐(o‐Bromophenoxymethyl)coumarins.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A Nucleophilic Addition of Acetone Enolate to (E)‐Alkyloxindolylideneacetates.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Unusual reduction of a lactone carbonyl in a Bu 3SnCl and Na(CN)BH 3 mediated radical cyclization of 3-( o-bromophenoxymethyl)coumarins

3-Chloromethyl coumarin was treated with different substituted 2-bromophenols in the presence of anhydrous potassium carbonate in refluxing acetone to afford a number of 3-(2-bromophenoxymethyl)coumarins 3a– f in 80–95% yield. These were then refluxed with tributyltin chloride and sodium cyanoborohydride in benzene under nitrogen, in the presence of a catalytic amount of azobisisobutyronitrile (AIBN) for 7–10 h to give spiro[chroman-3,3′-(2′ H)-benzofurans] 4a– f in 60–75% yields.

Regioselective Aryl Radical Cyclization: Access to Pyrimidine-Annelated Spiro Heterocycles Through 5-exo Ring Closure

Aryl radical cyclization of a range of 6-(2′-bromophen­oxymethyl)-1,3-dimethyluracils 4a-g was carried out with tributyltin chloride and sodium cyanoborohydride in the presence of AIBN for four hours to give exclusively the ‘5-exo’ cyclization products, 1,3-dimethylspiro[pyrimidine-6,3′-2′,3′-tetrahydrobenzofuran]-2,4-diones 5a-g in 92-95% yield. The starting materials were in turn prepared in 90-92% yield by refluxing 6-chloro methyl-1,3-dimethyl uracil with various 2-bromophenols or 2-bromonaphthol in acetone in the presence of anhydrous potassium carbonate for eight hours.

A Convenient Synthesis of Olefins via Deacylation Reaction.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A Nucleophilic Addition of Acetone Enolate to (E)-Alkyloxindolylideneacetates

The reaction of (E)-(2-oxo-1,2-dihydroindol-3-ylidene)acetic acid esters with dry acetone at 70°C in presence of aluminum oxide as a catalyst led to the formation of an addition product as a mixture of two isomers. When the same reaction was carried out in presence of morpholine as a base, the unexpected spiro-product was obtained beside the two isomers. Methylation of the latter with methyl iodide in acetone in presence of anhydrous potassium carbonate yielded the corresponding methylated products, whereas methylation of the starting material by the same procedure gave an N-methylated product and the unexpected dispiro-compound. The reaction mechanisms are considered and the structural assignments of the new compounds are based on the chemical and spectroscopic evidences. The structure of the dispiro-product was derived by X-ray analysis.

Cyclization of α‐Oxo‐oximes to 2‐Substituted Benzoxazoles.

AbstractFor Abstract see ChemInform Abstract in Full Text.