α-SUBSTITUIERTE PHOSPHONATE 50.1 Elektrochemisch generierte Basen als Reagenz für die Horner-Reaktion

Abstract

The radical anion 2 (electrochemically generated base), formed by electrochemical reduction of azobenzene (probase), is suitable for deprotonation of differently substituted phosphonates 4. α-Phosphonyl aniones 5, obtained by such approach, reacted in situ with carbonyl compounds to give α-substituted olefines 6. Similar reaction took place with stilbene as probase. —Side reactions with the solvent were observed with less acidic phosphonates, e.g. 4h.

Das bei kathodischer Reduktion von Azobenzen (Probase) entstehende Radikalanion 2 (elektrochemisch generierte Base) eignet sich zur Deprotonierung unterschiedlich substituierter Phosphonsäureester 4. Die so erhaltenen α-Phosphonylanionen 5 wurden in situ mit Carbonylverbindungen zu α-substituierten Olefinen 6 umgesetzt. Gleiche Reaktion trat mit Stilben als Probase ein.—Bei wenig aciden Phosphonaten wie 4h wurden Nebenreaktionen mit dem Lösungsmittel beobachtet.     

Studies on Spiroheterocycles,Part III: Synthesis of Diazaspiroundecanetetraone Derivatives Containing Biologically Active Heterocycles

Barbituric acid 2 upon Michael addition with dibenzal acetones 1a–c afforded the corresponding diazaspiro derivatives 3a–c . The base-catalyzed condensation of 3a–c with various aromatic aldehydes produces diarylidine derivatives 4a–l . The diarylidene compounds 4a–l on condensation with hydrazine, phenyl hydrazine, hydroxylamine, urea, guanidine carbonate, and hydrazine hydrate with acetic acid afforded their respective in situ oxidized products 5, 6, 7, 8, 9 , and 10 . The structures of the compounds are ascertained from their analytical and spectral data. Some of the compounds are screened for their biological activities against E. coli, B. cirroflagellosus, A. niger, and C. albicans.     

In situ Polypropylene Nanocomposites: Gas‐Phase Polymerization of Propylene in the Presence of Nanofillers using Nanosilica‐Supported‐Zirconocene Catalyst

This work concentrates on using the gas‐phase polymerization technique for the production of highly loaded nanocomposites. Filler loading levels near the vicinity of 40 wt% have been obtained using different nanofillers. Three different in situ Polypropylene (PP) nanocomposites, i.e., Cloisite‐20A filled polypropylene (CFPP), Kaolin filled polypropylene (KFPP) and nanosilica filled polypropylene (SFPP) have been prepared by gas‐phase polymerization. The catalyst used is Nanosilica‐Supported‐Zirconocene. The fillers used are Closite‐20A, Kaolin and nanosilica, respectively. These were pre‐treated with MAO (Methylaluminoxane) to inhibit their deactivating action on the catalyst because of the presence of either acidic or basic groups on their surfaces; in this way MAO acts as a co‐catalyst for the three polymerization reactions being discussed. Significantly higher molecular weight polypropylene was formed with nanosilica as the filler. The melting temperature and enthalpy is also observed to be comparatively higher in this case. However, in the case of other fillers, the molecular weights, as well as melting points, are comparatively lower. With the catalyst used, a mixture of crystalline and amorphous polypropylene was observed to form. Comparatively lesser amounts of crystalline polypropylene are also observed.     

Synthesis of Aza-Analogs of Natural and Artificial Desulfoglucosinolates

Abstract

Addition of 2,3,4,6-tetra-O-acetyl-β-D-l-thio-glucopyranose (3) on selected nitrilimines, generated in situ from the corresponding hydrazonoyl halides 5, gave the intermediate adducts 6 which were readily converted into glucosylthiohydrazonoates 7, the N-phenyl aza-analogs of desulfoglucosinolates.     

Synthesis of phosphinic acids on the basis of hypophosphites: VI. General methods for synthesis of pseudo-γ-glutamylpeptides

A general method for synthesis of 2-substituted pseudo-γ-glutamylpeptides, namely, [2-(hydroxycarbonyl)ethyl][3-amino-3-(hydroxycarbonyl)propyl]phosphinic acids I which are phosphinic acid analogs of γ-glutamylpeptides. Bis(trimethylsilyl) hypophosphite (IV) formed from ammonium hypophosphite (II) in situ was added to the respective α-substituted acrylate to form bis(trimethylsilyl) [2-R-2-(alkoxycarbonyl)ethyl]-phosphonites V. Treatment of compounds V in situ with excess dibromoethane followed by alcoholysis gave [2-R-2-(alkoxycarbonyl)ethyl](2-bromoethyl)phosphinic acids VI which without isolation were treated with excess triethyl orthoformate. The simultanious esterification and dehydrobromination led to [2-R-2-(alkoxy-carbonyl)ethyl](vinyl)phosphinates III which were isolated and characterized. The Michael addition of diethyl acetamidomalonate to vinylphosphinates III followed by acid hydrolysis of phosphinates VII without their isolation resulted in formation of target [2-R-2-(hydroxycarbonyl)ethyl][3-amino-3-(hydroxycarbonyl)]proly]phosphinic acids-pseudo-γ-glutamylpeptides I. Original Russian Text V.V. Ragulin, 2007, published in Zhurnal Obshchei Khimii, 2007, Vol. 77, No. 5, pp. 763–768. For communication V, see [1].     

Optimized Synthesis of Vinyl Ether Sugars and Vinyl Glycosides through Transfer Vinylation Catalyzed by (4,7‐Ph2‐phen)Pd(OOCCF3)2

Sugar vinyl ethers and vinyl glycosides are conveniently synthesized by catalytic transfer vinylation with butyl vinyl ether, which serves as both the solvent and source of vinyl. The air‐stable catalyst (4,7‐diphenyl‐1,10‐phenanthroline)Pd(OOCCF₃)₂ is prepared in situ from commercially available components.     

IMPROVED SYNTHESIS OF DIALKYLTHIOXAPHOSPHORANESULFENYL CHLORIDES AND BROMIDES

Abstract

Dialkylthioxaphosphoranesulfenyl chlorides and bromides can be conveniently prepared in the reaction of the corresponding thioamides with hydrogen chloride generated in situ with trimethylsilyl chloride and ethanol. Stability of the chlorides and bromides obtained by this method is high and the yields are quantitative.     

Generation of Selenoaldehydes via Retro Diels–Alder Reaction and Their Behavior in the Reaction with Some Enophiles

Abstract

The [4, 2] cycloadducts of selenoaldehydes and anthracene regenerate selenoaldehydes in situ quantitatively under neutral conditions via thermal retro Diels–Alder reaction. The reactions of selenoaldehydes generated by this method with 2-silyloxy-1,3-butadiene, 2-methoxyfuran, and 5-ethoxyoxazoles are described.     

Studies on Ptc-Wittig Reaction of Diphenyl Ylids

Abstract

The phase transfer catalyzed (PTC) Wittig reaction has the advantage of not requiring additional catalyst due to the catalytic property of phosphonium salt itself. This report presents the studies on such a reaction of diphenyl-, di-alkyl- and methyl-2-butenyl phosphonium ylids which are produced in situ from the corresponding phosphonium salts.     

Synthesis of an Advanced Precursor of Demethoxyviridin

The synthesis of a potential precursor 3 to demethoxyviridin (1b) is described. The centerpiece of this strategy was the conversion of the previously described dibromoolefin 6 to the masked alkyne β-hydroxyaldehyde 5 in a single step. Further elaboration then produced the alkyne oxazole 4, which on thermolysis, followed by in situ tautomerization and silylation, led directly to 3.

Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for full experimental and spectral details.     

Study on Nanofibers of Polyaniline via Interfacial Polymerization

Uniform polyaniline nanofibers were prepared by interfacial polymerization. The nanofibers had a diameter of 80 nm and a length of about 1μm. The effect of centrifugal force on the morphology of the nanofibers is discussed. In situ UV‐Vis spectra indicated that the interfacial polymerization process was similar to the solution polymerization process. An “expanded‐partly doped” stage of interfacial polymerization was observed for the first time in the in situ UV‐Vis spectra.     

Synthesis of Di- and Tri-Substituted Imidazole-4-carboxylates via PBu3-Mediated [3 + 2] Cycloaddition

Some new di- and trisubstituted imidazole-4-carboxylates were prepared from amidoacetic acids 3 in the present report. The key step to establish such imidazole-4-carboxylates stemmed from the PBu₃-mediated [3 + 2] cycloaddition between in situ–generated Δ2-oxazolinone 4 and ethyl cyanoformate6. Our results indicated that trisubstituted imidazoles 7–20 were afforded in better yields than those of disubstituted imidazoles 21–27.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

The Application of Microelectrodes for the Measurements of Trace Metals in Water

Abstract

The analytical approaches for the determination of trace concentrations of heavy metals in aquatic systems are briefly introduced. A detailed review on the recent advances of microelectrodes is presented, including the definitions, types, advantages, theory, and fabrication of microelectrodes. The application of microelectrodes on the measurements of trace metals in water is focused on the voltammetric‐, potentiometric‐, and in situ electrochemical sensors.     

Analysis of Plasmalogens by In Situ Reaction on Thin Layer Chromatograms

Abstract

An “in situ” hydrolysis method that attacks only the enol ether double bond of plasmalogen is described. Alkyl and unsaturated phosphollpids are not affected. Treatment of the plasmalogen on thin layers of silica gel with solutions of trichloroacetic acid in dilute hydrochloric acid result in more complete hydrolysis of the vinyl-ether linkage. After development of the chromatogram differential quantitation using copper sulfate charring (1) and densitometry will give the amount of vinyl-ether lipid present in the sample. The results of the method with ethanolamine plasmalogen are presented.     

Compatible Polyethylene/Polyvinyl Chloride Particle Hybrids Prepared by in‐situ Polymerization

Polyethylene/polyvinyl chloride (PE/PVC) hybrids were successfully prepared by a polymerization‐filling method. The catalyst for ethylene polymerization was supported on PVC particles, and ethylene was then polymerized in‐situ on the surface of the activated PVC. PVC particles could be well segmented and dispersed during in‐situ polymerization, and the prepared hybrids had an additional tangent peak between the glass transitions of polyethylene and PVC, indicating the formation of a compatible interlayer between nascent polyethylene and PVC during polymerization.     

Practical Preparation of Trimethoprim: A Classical Antibacterial Agent

An efficient, simple, and mild preparation of the classical antibacterial agent trimethoprim (1) was achieved in 85% overall yield from 3,4,5-trimethoxybenzaldehyde (2). First, the addition of propenenitrile (3) with dimethylamine almost quantitatively afforded 3-dimethylaminopropanenitrile (7). Then, by condensation of 7 with 2 as well as the continuous replacement of 3-dimethylamino group with aniline in situ, the key intermediate 3-anilino-2-(3,4,5-trimethoxybenzyl)propenenitrile (9) was obtained in an excellent yield of 91% with a one-pot procedure. Finally, the cyclization of 9 with guanidine nitrate furnished 1 in yields as good as 95% in the presence of the excessive sodium methoxide.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

New potential DNA intercalators of the carbazole series from indole-2,3-quinodimethanes: Synthesis,crystal structure,and molecular modeling with a watson-crick mini-helix

Summary 1-Alkylpyrano[3,4-b]indol-3-ones3 react via a Diels-Alder step with an aryne or N-phenylmaleimide to furnish the new [b]annellated carbazoles4–10 in a one-pot process. In an analogous procedure, the in situ generated N-benzoylindole-2,3-quinodimethane (13) reacted with quinones to furnish the dioxocarbazoles14–16. Compounds4–8 and14–16 with a coplanar skeleton are members of a class of potential DNA intercalators, as has been shown for5 and8 by X-ray structural analysis. On the basis of the geometries determined by X-ray crystallography, the intercalative binding of these molecules with a Watson-Crick mini-helix was predicted by molecular modeling methods.

---

Neue potentielle DNA-Interkalatoren der Carbazol-Reihe aus Indol-2,3-chinodimethanen: Synthese, Kristallstruktur und Molecular Modeling mit einer Watson-Crick Minihelix

Zusammenfassung 1-Alkylpyrano[3,4-b]indol-3-one3 reagieren über einen Diels-Alder-Schritt mit Arin oder N-Phenylmaleinimid zu [b]annellierten Carbazolen4–10 in einer Einstufenreaktion. In analoger Weise reagiert ein in situ erzeugtes N-Benzoylindol-2,3-chinodimethan13 mit Chinonen zu den Dioxocarbazolen14–16. Die Verbindungen4–8 und14–16 gehören infolge ihrer coplanaren Struktur zur Klasse potentieller DNA-Interkalatoren. Auf der Basis von Röntgenstrukturanalysen von5 und8 wird die interkalative Bindung mit einer Watson-Crick Minihelix durch Molecular Modeling vorhergesagt.

     

SULPHENE INTERMEDIATES IN THE SYNTHESIS OF POLY(P-BENZENE-SULPHONAMIDES) AND POLY(P-BENZENE SULPHONATES)

Abstract

Various sulfides are easily oxidized selectively to the corresponding sulfoxides in quantitative yields by iodosylarene (ArIO) catalyzed by metalloporphyrin (TPPM(III)Cl (M [dbnd] Fe, Mn)). The oxidation system is demonstrated to be a possible model for monooxygenase in the study of the stereochemistry of these sulfoxides. Metalloporphyrin-iodosylarene can initially equilibrate with the oxometalloporphyrin (TPPM(V)=O·Cl) formed in situ. The initial process may involve one-electron transfer from the sulfide to the intermediate oxometalloporphyrin followed by coupling of two resulting charged products, and/or nucleophilic attack of sulfide on oxometalloporphyrin oxygen. The overall reactions are depicted by paths with different electron demands from the results of Hammett plots.     

HIGHLY STEREOSELECTIVE SYNTHESIS OF DIALKYL 2-ALKYLIDENE GLUTARATES

Nucleophelic substitution of dialkyl (E)-2-bromomethylene glutarates 2 by magnesium dialkyl cuprates generated in situ provided a regio and highly stereoselective methodology for the synthesis of dialkyl 2-alkylidene glutarates 3 in good yields.     

Microwave Assisted Synthesis of Fluorinated Hexahydro 1,3,5‐Triazine Derivatives in Aqueous Medium and One Pot Synthesis of 1,2,4‐Triazolo(4,3‐a)1,3,5‐triazines

Abstract

A multi‐component condensation of substituted phenylthiourea/urea, aqueous formaldehyde and substituted aromatic/heterocyclic amines lead to 2‐thioxohexahydro‐1,3,5‐triazines (4) in aqueous medium under microwave irradiation in 30–60 sec in quantitative yield with reasonable purity. Further, triazolo[4,3‐a]triazines were also prepared by a one‐pot reaction of ‘in situ’ synthesized triazinyl hydrazine (7) with CS₂ (9).