Synthese arylsubstituierter 2-Pyrimidinamine,Dihydro-2-pyrimidinamine und Pyrimido[1,2-a]pyrimidine durch Reaktion von Guanidin mit Chalkonen

4- and 4-methoxy-, 4-hydroxy- and 2-hydroxychalcone4 e,k,f andg, respectively, are transformed by action of guanidine in benzene to yield 4-(4-methoxyphenyl)-6-phenyl-2-pyrimidinamine (6 e=6 k) and hydroxyphenylpyrimidinamines6 f andg, respectively. In contrast, 4- and 4-chlor-, 4-brom- and 4-phenylchalcone4 h,l–n resp. react with guanidine under analogous conditions to give 4,6-diaryl-1,4-dihydro-2-pyrimidinamines5 h,l–n. The bases5 h,l–n also tend to aromatize, but they can be stabilized by transformation into salts5 h,l–n · HCl with hydrochloric acid. Heating of5 n inDMF under atmospheric oxygen yields 4-(4-biphenyl)-6-phenyl-2-pyrimidinamine (6 n). Action of guanidine on 4-nitrochalcone4 o in chloroform affords 2-amino-4-nitrophenyl-6-phenyl-tetrahydro-4-pyrimidinol8 o, which is transformed by hydrochloric acid into 6-nitrophenyl-dihydropyrimidinamine-hydrochloride5 o · HCl. Treating of the latter with sodiummethylat in methanol yields the very stable dihydropyrimidinamine5 o. Action of guanidine on 4-chlor- and 4-bromchalcone4 h andm respectively (in addition to5 h andm) yields 2,4,6,8-tetraaryl-1,4-dihydro-2H-pyrimido[1,2-a]pyrimidines7 h andm, respectively.

Herrn Prof. Dr.Erwin Schauenstein mit den besten Wünschen zum 65. Geburtstag gewidmet.     

Über cyclische Guanidin—Mesityloxid- und Guanidin—Phoron-Kondensate

The basic product synthesized byTraube andSchwarz from mesityl oxide and guanidine has not been 4.4.6-trimethyl-4.5-dihydro-2-pyrimidinamine (1), but a mixture containing the 4.4.6-trimethyl-3.4-dihydro-2(1H)-pyrimidinimine (resp. an isomeric pyrimidinamine)2 a (resp.2 b, 2 c) and the dimeric 4.4′-methylenedi[2(1H)-pyrimidinimine] (resp. an isomeric methylenedipyrimidinamine)3 a (resp.3 b, 2 c) and the dimerisation reaction were studied in a series of experiments. The product of the reaction of guanidine and phorone is not the guanidinopropylpyrimidine8 ⁴, but the 4.4′-spirobi[2(1H)-pyrimidinimine] (resp. a spirobipyrimidinamine)11 a (resp.11 b, 11 c). No determination was possible on the basis of NMR whether the condensation products of guanidine—in solutions ofDMSO-d₆—are pyrimidinimines (2 a, 3 a, 11 a) or pyrimidinamines (2 b resp.2 c, 3 b resp.3 c, 11 b resp.11 c) or mixtures of the isomeric compounds. The NMR-and mass spectra of2 a (resp.2 b, 2 c),3 a (resp.3 b, 3 c),11 a (resp.11 b, 11 c) and their derivates are discussed.     

The Brownian loop soup

We define a natural conformally invariant measure on unrooted Brownian loops in the plane and study some of its properties. We relate this measure to a measure on loops rooted at a boundary point of a domain and show how this relation gives a way to chronologically add Brownian loops to simple curves in the plane.Cornell University; Research supported in part by the National Science FoundationUniversité Paris-Sud and IUFMathematics Subject Classification (2000):60J65, 81T40     

Immobilized β-cyclodextrin on surface-modified carbon-coated cobalt nanomagnets: reversible organic contaminant adsorption and enrichment from water

Surface-modified magnetic nanoparticles can be used in extraction processes as they readily disperse in common solvents and combine high saturation magnetization with excellent accessibility. Reversible and recyclable adsorption and desorption through solvent changes and magnetic separation provide technically attractive alternatives to classical solvent extraction. Thin polymer layered carbon-coated cobalt nanoparticles were tagged with β-cyclodextrin. The resulting material reversibly adsorbed organic contaminants in water within minutes. Isolation of the immobilized inclusion complex was easily carried out within seconds by magnetic separation due to the strong magnetization of the nanomagnets (metal core instead of hitherto used iron oxide). The trapped molecules were fully and rapidly recovered by filling the cyclodextrin cavity with a microbiologically well accepted substitute, e.g., benzyl alcohol. Phenolphthalein was used as a model compound for organic contaminants such as polychlorinated dibenzodioxins (PCDDs) or bisphenol A (BPA). Fast regeneration of nanomagnets (compared to similar cyclodextrin-based systems) under mild conditions resulted in 16 repetitive cycles (adsorption/desorption) at full efficiency. The high removal and regeneration efficiency was examined by UV-vis measurements at chemical equilibrium conditions and under rapid cycling (5 min). Experiments at ultralow concentrations (160 ppb) underline the high potential of cyclodextrin modified nanomagnets as a fast, recyclable extraction method for organic contaminants in large water streams or as an enrichment tool for analytics.     

On Conformally Invariant CLE Explorations

We study some conformally invariant dynamic ways to construct the Conformal Loop Ensembles with simple loops introduced in earlier papers by Sheffield, and by Sheffield and Werner. One outcome is a conformally invariant way to measure a distance of a CLE₄ loop to the boundary “within” the CLE₄, when one identifies all points of each loop.     

Phosphate starvation as an antimicrobial strategy: the controllable toxicity of lanthanum oxide nanoparticles

Lanthanum oxide nanoparticles were utilized to scavenge phosphate from microbial growth media for the use of targeted nutrient starvation as an antimicrobial strategy. Only in phosphate poor environments a toxic effect was observed. The effect was shown on Escherichia coli, Staphylococcus carnosus, Penicillium roqueforti, and Chlorella vulgaris.     

Über N1- und N2-substituierte 2-Amino-5,6-dihydro-4(1H)-pyrimidinone

The reactions of the monosubstituted guanidines2 b-h with methyl acrylate in dimethylformamide or ethanol as solvent preferentially afford 1-substituted 2-amino-5,6-dihydro-4(1H)-pyrimidinones6 b-h. The structures of 1-hexyl- and 1-benzyl-4-pyrimidinones6 c, e and of the picrate of 1-phenylpyrimidinone6 g were proved by comparison with authentic samples, which were prepared from N-substituted ethyl 3-amino-propionates14 c, e andg and cyanamide. Accordingly,6 g is not identical with authentic 2-phenylaminopyrimidinone7 g (prepared from 2-methylthio-4-pyrimidinone10 and 2-thioxo-4-pyrimidinone12 respectively, compare¹⁰).N,N-Disubstituted guanidines2 i-m react with methyl acrylate in dimethylformamide as solvent to afford N²,N²-disubstituted 2-amino-5,6-dihydro-4-(1H)-pyrimidinones7 i-m. Action of morpholine-4-carboxamidine (21) on methyl acrylate in ethanol yields 2-morpholinopyrimidinone71 as byproduct and 3-ethoxy-N-[morpholino(amino)methylene]propionamide (91) as mainproduct.

Herrn Prof. Dr.Robert Ott mit den besten Wünschen zum 60. Geburtstag gewidmet.     

1-Chlormethylisatin—ein neues reagens zur Identifizierung von Carbonsäuren

Zusammenfassung 1-Chlormethylisatin (2) reagiert mit den Salzen von Monobzw. Dicarbonsäuren in Wasser—Dimethylformamid leicht zu 1-Isatinylmethyl- bzw. Di-(1-isatinylmethyl)estern3 bzw.4. 68 derartige Ester wurden dargestellt und tabelliert; sie sind zur Identifizierung von Carbonsäuren bestens geeignet.

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1-Chloromethylisatin—a new reagent for identifying carboxylic acids

1-Chlormethylisatin (2) reacts with salts of mono- resp. dicarboxylic acids in water—dimethylformamide easily to yield 1-isatinylmethyl- resp. di(1-isatinylmethyl)esters3 resp.4. 68 of these esters were synthesized and tabulated; they are a useful means for characterizing carboxylic acids.

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Mit 2 Abbildungen

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Herrn Prof. Dr.E. Ziegler zum 60. Geburtstag gewidmet.