Showing papers in "Phosphorus Sulfur and Silicon and The Related Elements in 1996"

Recent advances in the synthesis of sulfoxides from sulfides

Abstract: This review deals with the various recent advances in the selective oxidation of sulfides to sulfoxides. Non-stereoselective, diastereoselective as well as enantioselective methods are covered. A considerable number of new oxidizing agents have been reported in the last ten to twelve years including those aiming to replace m-chloroperbenzoic acid as the classical sulfide oxidant: Oxone®. dimethyldioxirane, among others. Chiral sulfoxides are especially important in modern asymmetric synthesis, their obtention from prochiral sulfides by Davis' oxaziridines and modifications of Sharp-less procedure are discussed, along with other less common methods. The most newly reported microbiological and enzymatic oxidations are also included.

Elucidation of a Pharmacophore for the Bisphosphonate Mechanism of Bone Antiresorptive Activity

Abstract: Our recent discoveries in the field of phosphonate bone antiresorptive agents include analogs of the pyridine containing bisphosphonate NE-58095 (Risedronate) such as the pyridinium bisphosphonate NE-10575, the pyridine phosphonocarboxylate NE-10790, and the pyridine phosphonophosphinate NE-10864. We believe these analogs differ at key recognition sites in the putative cellular pharmacophore and thus offer important structure-activity learnings.

Intermediates in the thermal decomposition of normal copper(ii), nickel(ii) and cobalt(ii) selenite dihydrates

Abstract: Thermal decomposition of normal transition metal selenite dihydrates, MSeO2.2H2O; M [dbnd] Cu(II), Ni(II), Co(II) was traced by TGA/DTA measurements from 50–700°C. The thermal products were obtained by heating the selenites in an air-oven to different temperatures, as determined from TGA/DTA curves, where different coloured products are obtained. The structures of the start selenites and the thermal intermediates were determined by chemical analyses and FT-IR spectral measurements. The start selenites proved to be equilibrium mixtures of the selenite, hydrogenselenite and/or pyroselenite anions. Gradual changes occurred in the FT-IR spectra of the nickel and cobalt selenites on thermal treatment till 225°C where, due to water loss, merely selenite anions are observed. In the case of the copper selenite, the selenito mixture persists till 250°C and the only change observed in the final product is the disappearance of one of the structurally non-equivalent water molecules present in the start selen...

Synthesis and radiation stability of novel thiazolopyrimidines with expected antifungal activity

Abstract: A number of thiazolopyrimidines (II–VII) were prepared through interaction of 6-methyl-4(4′-chlorophenyl)-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylic acid ethyl ester (Ia) with many reagents. The antifungal activity of all prepared compounds have been determined using Dithane M-45 as a standard fungicide. Some compounds showed a high fungicidal activity equivalent to that of the standard towards Aspergillus niger and Aspergillus ochraceus. Also some biologically active compounds were subjected to gamma irradiation and the structures are stable.

Mesoionic 2-n-cycloalkylamino-5-alkyl-1,3-dithiolium-4-thiolates

Abstract: Seven 2-(N-cycloalkylamino-1,3-dithiocarbamoyl)-carboxylic acids and seven mesoionic 2-N-cycloalkylamino-5-alkyl-1,3-dithiolium-4-thiolates have been conveniently synthesized. They were characteriz...

A Horner-Wittig Synthesis of 1-Chlorovinyl Sulfoxides.

Abstract: 1-Chlorovinyl sulfoxides 1 were prepared by Horner-Wittig reaction of the readily accessible [(α-chloro)sulfinylmethyl)diphenylphosphine oxides 2 with aldehydes. Excellent Z-selectivity was observed in most cases.

1-aminophosphonic acids and esters bearing heterocyclic moiety. part 2.1 pyridine, pyrrole and imidazole derivatives

Abstract: The benzylic amines (benzylamine, benzhydrylamine and benzyl carbamate) were applied in the synthesis of aminophosphonates derived from pyridine, pyrrole and imidazole. The Schiff bases obtained from corresponding heterocyclic aldehydes and benzylic amines were caused to react with diphenyl phosphonate or dibenzyl phosphonate to form corresponding heterocyclic aminophosphonates in good yields. The N-(benzylamino)-phosphonates were deblocked by catalytic hydrogenolysis. The benzhydryl group from the phosphonates was removed by acidic hydrolysis, and the carbobenzyloxy group from the phosphonates can be easy removed by treatment with a solution of 30% HBr in acetic acid, as well. It was found that during acidic hydrolysis of 2- and 4-pyridylmethylaminophosphonates a rearrangement occurred. combined with a cleavage of C—P bond in the phosphonate molecules and subsequent formation of the corresponding amines.

Synthesis and its stereochemistry of aminophosphonic acids derived from 5-hydroxymethylfurfural

Abstract: Some dialkyl N-substituted-α-amino-α-furylmethanephosphonates were synthesized via the addition of dialkyl phosphites to corresponding imines in mild conditions in a short time. When an imine is chirally N-substituted the reaction is stereoselective. Stereochemical aspects of the reaction in the light of Cram rules is discussed in this paper.

Mono- and dialkylation of isopropyl phosphinate-a simple preparation of alkylphosphinate esters1

Abstract: Base-catalysed alkylation of isopropyl phosphinate with primary alkyl halides under mild conditions affords the corresponding alkyl phosphinate esters in fair to excellent yields

1,2,4-selenadiphospholes—novel heterocyclic compounds containing low-coordinated phosphorus atoms1

Abstract: The thermal reactions (at 120°C) of the 1,2,3-selenadiazole 8 with the phosphaalkynes 6a and 6b gave rise to the previously unknown title compounds in 17% and 16% yield, respectively. These compounds are formed by a sequence of [3 + 2]-cycloreversion and cycloaddition reactions.

Advances in trifluoromethylating phosphorus compounds

Abstract: The System CF3I/Me3P is re-investigated and Me2PCF3, Me4P+γ, (CF3)2PMe3, Me3PI2, [Me3(CF3)P]+γ are found as products. Using CF3Br/P(NEt2)3 the phosphines R1 2PCF3 and R1P(CF3)2 (e.g. R1 = Me, iPr, NEt2) can be obtained which are precursors either for phosphoranes (e.g. 1,2λ5σ5-oxaphosphetanes) or phosphonium salts (e.g. [R1 2(Me)PCF3]+X− or [R1(Me)P(CF3)2X−]. The latter are deprotonated to furnish methylene phosphoranes R1 2(CH2=)PCF3 or R1(CH2=)P(CF3)2, reactive synthons. From CF3Br/P(NEt2)3/P(OPh)3 the phosphine P(CF3)3 is available, which turned out to be a potent electrophile. Amido phospites ROP(NEt2)2 and halides R2X (R2=CCl2CF3, X=Cl; R2=CF=CFCF3, X=F; R2=C6F5, X=Br, I; R2=C(CF3)3, X=Br; R2=SCF3, X=CF3) undergo an ARBUZOV reaction.

Reactions with cyanothioacetamide derivative: synthesis and reactions of some thieno[2,2-b]pyridine, pyridothienopyridazine, pyrazolo[3,4=b]pyridine and pyridopyrazolo-1,2,4-triazine derivatives

Abstract: Thiocarboxamidocinnaonihile derivatives 3a,b reacted with ethyl-benzoylacetate (4) to give pyridinethione derivatives 5a,b which were used as starting materials for synthesis of several hetero-cyclic compounds. Reactions with phenacyl bromides 6a,b, chloroacetone (8), α-chloraacetylacetone and methyl iodide gave thieno[2,3-b]pyridines 7a-d. 2-S-methylacetylpyridine derivatives 9a,b 2-S-methyldiacetyl pyridine derivatives 114b and 2-S-methyl pyridine derivatives 14a,b respectively. Several cyclization reactions were performed with 10% KOH, nitrous acid and hydrazine hydrate to give an additional ring on 9a,b, 10a,b, 11a,b and 14a,b.

Phosphite Addition to Carbonyl Group and Phosphoryl Migration Under Phase Transfer Catalytic Circumstances

Abstract: The rearrangement of α-hydroxyphosphonates to phosphates under PTC conditions usually run in a different way and gives better yield as that found in homogenous system.

Heterocyclen als liganden xxii. 2-chalkogenoimidazoline als liganden in pentacarbonylmetall-komplexen

Abstract: The chalcogenoimidazoline complexes N—CMe—CMe—NR—C=X·M(CO)3 (VIII-XI; R = Me, iso-Pr; X = S, Se, Te; M = Cr, Mo, W) are obtained from the metal hexacarbonyls (M = Cr, Mo, W) and the chalcogenoimidazolines IV-VII. In these complexes the chalcogeno ligands exhibit strong donor properties according to the sequence Te > Se > S which is demonstrated by n. m. r. and i. r. data. The X-ray structures of N(iso-Pr)—CMe—CMe—N(iso-Pr)—C=X·Cr(CO)3 (X = S; Se; VIIIa, IXa) are reported.

Synthesis of 1-aminoalkanephosphonic acid derivatives containing furan moiety. part ii: first synthesis of (2-furyl)aminomethane phosphonic acid1

Abstract: The synthesis of (2-furyl)aminomethanephosphonic acid from furfural via corresponding imine, dibenzyl ester and N-benzylsubstituted acid is presented. The synthesis was performed by the hydrogenolysis of a corresponding N-benzylsubstituted dibenzyl ester.

Synthesis and structure of some stable phospholane-phospholanes

Abstract: Bicyclophosphites based on linear 1,2,3-triols with terminal substituents were found to be stable. Thus a series of hitherto unknown phospholane-phospholane esters, including optically active ones, was synthesized and their promise for synthetic use was demonstrated. The structure of the new compounds was proved by 1H, 13C and 31P NMR spectroscopy and, for one of them, by X-ray analysis.

SYNTHESIS AND MOLECULAR STRUCTURE OF Mes(H)P-P(H)Mes (Mes = 2,4,6-Me3C6H2)

Abstract: Cp˚2Zr(PMesPMes) (Cp˚ = η5-C5Me4Et. Mes = 2,4,6-Me3C6H2) reacts with phenylacetylene with cleavage of the Zr-P bonds and formation of Mes(H)P-P(H)Mes (1). 1 is also obtained from LiPHMes and 1,2-dibromoethane. The 31P NMR spectrum of 1 shows the presence of both isomers (d,l and meso form). A crystal structure determination carried out on meso-Mes(H)P-P(H)Mes showed that in the solid state the bulky Mes groups have a trans arrangement.

THE PREPARATION AND CHARACTERIZATION OF SOME FLUORINATED α-AMINOARYLMETHANEPHOSPHONIC ACIDS

Abstract: α-Aminoarylmethanephosphonic acids have been prepared with a range of fluoro, fluoroalkyl, or fluoroalkoxy substituents in the benzene ring (4-F, 3-F, 2-F, 3,4-F2, F5, 4-CF3, 3-CF3, 4-CF3O, and 3-CF3O). These compounds have relatively low aqueous solubility and their NMR spectra (1H, 13C, 31P and 19F) were therefore recorded in D2O in the presence of an excess of alkali. Under these conditions, the ring substituents appear to have little effect on δH (15–18 ppm), or on the 1H and 13C parameters for the benzylic group (α-CH), which are mainly in the ranges observed for other types of α-aminoarylmethanephosphonic acids under alkaline conditions (δH, 3.8–4.0 ppm, 2 J PH 15.3–16.5 Hz; δc 57–58 ppm, 1 J PC 128–132 Hz). For those examples with fluorine in the ortho position (i.e., the 2-fluoro and pentafluoro derivatives) a slightly higher field chemical shift was observed for the benzylic carbon atom (δc 50–51 ppm). In the fast-atom bombardment mass spectra, pseudo-molecular ions, MH+, and ions result...

A simple one pot synthesis of 1-chlorophospholes

Abstract: The chemistry of phospholes has been extensively investigated and reviewed.1,2 Among the numerous phosphole derivatives, however, the 1-halo functionalized systems are relatively scarce3 and have not been systematically investigated. The synthesis of 1-halophospholes has been achieved from organozirconium intermediate,3a,b a 1,1′-biphosphole,3c a 1,4-dilithio compound,3d and a diazonium salt.3e As these syntheses involve rather complicated multistep procedures we decided to investigate a simple approach: the direct conversion of a dilithio compound with phosphorus chloride to furnish the 1-halophosphole system. Our first objective was the synthesis of 1-chloro-2,3,4,5-tetraphenylphosphole from 1,4-dilithio-1,2,3,4-tetraphenylbutadiene and phosphorus trichloride3d (Scheme 1)

Zur oxidation von 2-selenoimidazolinen mit iod1

Abstract: The stepwise oxidation of 2-selenoimidazolines 1 (ImSe; Im = 1,3-dihydro-1,3,4,5-tetraalkyl-2H-imi-dazol-2-ylidene) leads to a series of carbene stabilised selenium iodine compounds whose composition depend from the stoichiometry and the substituents at the nitrogen atoms. No diselenides or selenium(IV) compounds have been detected. The X-ray structures of the compounds [ImSeSelm]2+ (3c), (ImSel2)2I2 (5c) and (ImSel)I3 (6b) are reported.

Synthesis of 2-chloroethylnitrososulfamides (cens) via a transsulfamoylation reaction

Abstract: In order to synthesize the series of 2-chloroethylnitrososulfamides (CENS), a procedure using the nucleophilic exchange of an activating group of both the sulfamoyl esters and amides by several amines was developed. The N-oxysuccinimide sulfamate ester was revealed as the most reactive sulfamoyl group donor. This transsulfamoylation procedure allows the preparation of title compounds, especially the derivatives of amino acid esters in two steps in a 75–80% yield.

Zwitterionic species from triisopropylphosphine and 2-cyanoacrylates: synthesis, structure and properties

Abstract: Triisopropylphosphine reacts with 2-cyanoacrylates with formation of the P-zwitterionic species 2a and 2b. The reaction of 2b with trimethylsilyltriflate, in the presence of traces of water, leads to the phosphonium triflate 3. 2b is alkylated at the carbon atom with methyl iodide with formation of the phosphonium iodide 4. The initially formed adducts of the zwitterionic species 2a and 2b with tosyl azide and with tosyl isocyanate are thermodynamically unstable. In the first case, the final products of the reaction are tosyl iminotriisopropylphosphine imide 6 and 2-cyanoacrylate polymers. In the second case, the reaction leads to the zwitterionic product 8, and, in the presence of traces of water, to the molecular complexes 9a and 9b. The reaction of the zwitterionic species 2a and 2b with methylisocyanate proceeds in an unusual way, resulting in the formation of the zwitterionic species 12a and 12b, as a result of the insertion of methylisocyanate into the C[sbnd]C bond of the starting zwitteri...

CLAY-CATALYZED THIOALKYLATION OF THIOPHENES AND BENZO[b]THIOPHENES

Abstract: A method for the direct thioalkylation of thiophene (1) and benzo[b]thiophene (7) by reaction of either heterocycle with an alkyldisulfide using a ZnCl2-modified montmorillonite clay catalyst is described. The clay-catalyzed reaction of 1 with excess dimethyl disulfide (DMDS) over 24 hours in refluxing chlorobenzene yielded a mixture of bis-, tris-, and tetrakis(methylthio)thiophenes (2–5) from which 2,3,5-tris(methylthio)thiophene (4a) and tetrakis(methylthio)thiophene (5) could be isolated in modest yield. Prolonging the reaction time gave (4a) and 5 in isolated yields of 21 and 16% respectively. Carrying out the same reaction in a sealed autoclave at 150°C with an air overpressure resulted in a clean and rapid (5 h) conversion of thiophene to the tetramethylthio-derivative 5 in moderate isolated yield (50%). In a similar manner 7 could be converted to 2,3-bis(methylthio)benzo[b]thiophene (8a) or 2,3,6-tris- and 2,3,6,7-tetrakis(methylthio) derivatives 9 and 10a by clay catalyzed reactions with...

Fused cyanopyrimidines: part ii synthesis and reactions of fused cyanopyrimidine derivatives as affecting enzymatic agents

Abstract: Some new fused heterobicyclic systems, such as thiazolo[3,2-a]-pyrimidin-5-one (3), 2,3-tetrahydrothiazolo[3,2-a]pyrimidin-5-one (5), 2,4-tetrahydrothiazino[3,2-a]pyrimidin-3,6-dione (6), 3-dihydrothiazino[3,2-a]pyrimidin-2,4,6-trione (7), 3-arylidenethiazino[3,2-a]pyrimidin-2,4,6-trione (8) and/or the related nitrogen compounds, such as 2,3-tetrahydroimidazolo[3,2-a]-pyrimidin-5-one (9), 1-aryl-2,3-tetra-hydroimidazolo[3,2-a]pyrimidin-5-one (11), quinazolino[3,2-a]-pyrimidin-6,8-dione (12) and 3-mercapto-1,2,4-triazolo[4,3-a]pyrimidin-5-one (14) have been synthesized by the interaction of 2-mercapto-4-arylidene-5-cyanopyrimidin-6(1H)one (1) with α,β-bifunctional nitrogen, oxygen and/or sulfur compounds The structures have been characterized by elemental analyses, IR, UV, 1H NMR and mass spectral data Some newly prepared compounds revealed a moderate effect on the activity of cellobiase produced by Aspergillus nidulans

Structure-Activity Studies of Aminophosphonic Derivatives of Fluorene

Abstract: Structure-activity dependence of 51 aminofluorenephosphonic acid derivatives was studied. It was found that herbicidal activity of the studied compounds depends on the hydrophobic parameters, and to a smaller extent to the electronic parameters of the substituents on nitrogen and phoshorus atoms and is independent on their steric parameters.

Reactions with cyanothioacetamide and its derivatives: synthesis and characterization of several new pyridine and annelated pyridine derivatives

Abstract: Several new pyridines and annelated pyridines were synthesised via the reactions of some pyridinethiones with a variety of activated halogenomethyl containing reagents and hydrazines. Structures were established on the basis of elemental analysis and spectral data.

Synthesis of 8-substituted-2-carboxy-4-(4-fluorophenyl)-2,3-dihydro-1,5-benzothiazepines

Abstract: The reactions of 5-substituted-2-aminobenzenethiols with δ-(4-chlorobenzoyl)- and δ3-(4-bromobenzoyl)acrylic acids have been carried out in methanol containing traces of glacial acetic acid to yield in a single step, 8-substituted-2-carboxy-4-(4-chlorophenyl and 4-bromophenyl)-2,3-dihydro-1,5-benzothiazepines, the substituents being CI, Br as halogen; CH3 as alkyl, and OCH3 and OC2H5 as alkoxyl. The structural assignments have been made by a study of microanalyses of the elements and IR, 1H NMR and mass spectral studies of the title compounds.

Synthesis of some new thiadiazole, selena, triazine, thiazole and cyanopyridine derivatives with assay for their antitumor activity

Abstract: The synthesis of 2-methyl-3-(4′-acetylphenyl)-quinazol-4-one II was accomplished by the condensation of the benzoxazine I with 4-aminoacetophenone. The semicarbazone III was obtained from II by refluxing with an equimolar amount of semicarbazide hydrochloride in ethanol. The latter compound was then subjected to oxidative cyclization either by thionyl chloride or selenium dioxide to give thiadiazole and selena derivatives IV and V, respectively. Compound V was condensed with different aromatic amines to yield the corresponding Schiff's bases VI. The phenylglyoxal derivative VII was prepared by oxidation of II with selenium dioxide. Condensation of VII with thiosemicarbazide in ethanol in the presence of potassium carbonate gave 3-mercapto-1,2,4-triazine derivative VIII. Treatment of II with bromine in acetic acid gave the bromo derivative IX which was reacted with thiourea to give 2-aminothiazole derivative X. Cyanopyridine-2-(1H)-thione derivatives XIVa-h were obtained via the reaction of arylme...

A GENERAL SYNTHETIC APPROACH TO α-HYDROXY PHOSPHORYL COMPOUNDS

Abstract: A general synthetic way for the preparation of a large variety of α-hydroxy phosphoryl compounds is here reported. In our approach, trialkyl phosphite is added in equimolar amount, at room temperature and under strong acidic conditions (HCI gas), to the corresponding carbonyl compound dissolved in anhydrous dioxane. The reaction is quite exothermic and cooling is often needed; 10–15 min reaction time is sufficient in order to assure almost quantitative yields in the desired product, which can be easily isolated as a white pure solid by concentration of the reaction mixture. The reaction works in an excellent way with all kind of aliphatic, aromatic and heteroaromatic aldehydes. The α-hydroxy phosphonates obtained were fully characterized by 1H- and 31P-NMR, by FAB-MS and IR spectroscopy. When o-carboxybenzaldehyde was used as a reagent, cyclic dialkyl phthalide-3-phosphonates were obtained in very good yields (≥90%).

Neue thioether und disulfidverbindungen aus mono(arylthio)substituiertem 2-nitrotetrachlor-1,3-butadien und neue thioether mit butadien-, butin und buteninstruktur aus hexachlorbuten

Abstract: 2-Nitro-tetrachlor-mono(4-methylphenylthio)-1,3-butadiene (la) in water-ethanol mixture in the presence of sodium hydroxide reacted with 2,2-Oxydiethanethiol (2a) to give heterocyclic thiother 3a, disulfide compound 7a and bis(arylthio)-1,3-butadiene 8a. Compound la from reaction with 1,4,8,11-tetrathiaundecan (2b) in ethanol yielded cyclic thioether 3b, disulfide 5b, 8b and tris(arylthio)-1,3-butadiene 9b compounds. 2-Nitro-tetrachlor-mono(4-chlorphenylthio)-1,3-butadiene (16b) gives 3c, 4c and 6c by the reaction with dithiol 2a in EtOH containing sodium hydroxide. From reaction compound lb with 2b in EtOH yielded 3d, 10d and 8b compounds. Compounds 12b and 13b, have been obtained from lb and cystamine in EtOH at room temperature. 14 yielded previously unknown 16a-b, 17a-b, 18a, 17c and 19a-c thioether compounds from reaction with thiols (15a-c). Compound 21 gives 22a, 23a and 24a by the reaction with octanthiol in DMSO.