Mehrstufiges Verfahren zur Herstellung von Deuteropropanon auf katalytischem Weg

A novel equipment for a multistep deuteration process of organic compounds was developed. As an example the deuteration of propanone by deuterium oxide over magnesia and thoria was examined. The degree of deuteration of the organic compound and of the catalysts was determined by on-line mass-spectrometry. Percentages of deuterium uptake of the organic compound up to 90% were found. These degrees of deuteration were higher than those measured at the catalysts' surface. This fact can be explained by the kinetic isotope effect.

     

New Cell Growth-Inhibitory Cyclohexadienone Derivatives from Hypericum calycinum L.

The crude petroleum-ether extract of the aerial parts of Hypericum calycinum L. (Guttiferae) exhibited in vitro growth-inhibitory activity against the Co-115 human colon carcinoma cell line. Bioassay-guided fractionation of this extract allowed the isolation of the cyclohexadienone derivatives 1–5 , four of which are previously undescribed compounds. The structures of the known chinesin II (1) and of 2 (hypercalin A) were established by ¹H- and ¹³C-NMR spectroscopy and were confirmed by X-ray analysis of their crystalline mixture which revealed the complete relative configuration of both compounds. The structure of 3 (hypercalin B) was elucidated by means of extensive 1D- and 2D-NMR experiments, including DQ-COSY, HETCOR and LR-HETCOR. The structure of compound 4 (hypercalin C) was established by ¹H- and ¹³C-NMR spectroscopy and confirmed by X-ray analysis to be the 3,5-dihydroxy-4-{[(1R*,2S*, 5S*)-2-hydroxy-2-methyl-5-(1-methylethenyl)cyclopentyl]methyl}-6,6-bis-(3-methylbut-2-enyl)-2-(2-methylpropanoyl)cyclohexa-2,4-dien-1-one. The structures of the higher isomeric homologues 5a/5b were deduced by comparison of their UV, ¹H-, and ¹³C-NMR spectra with those of 4 . The isolated compounds appeared to be related to chinesin I and II previously isolated from Hypericum chinense L. and were responsible for the growth-inhibitory activity of the extract against the Co-115 human carcinoma cell line. Moreover, 1/2 and 3 showed molluscicidal activity against the schistosomiasis-transmitting snail Biomphalaria glabrata.     

Preparation of trimethyl-2-hydroxyethylarsonium (arsenocholine) compounds

Trimethyl-2-X-ethylarsonium salts (X=OH, Cl, Br, CH₃COO; anion=Br) and trimethyl-2-diethoxyethylarsonium bromide were prepared from trimethylarsine and the appropriate organic bromides in sealed tubes at elevated temperatures or by refluxing the neat reagents. The yields ranged from 33 to 85%. Anion exchange reactions produced the arsonium iodides, nitrates, acetates, tosylates, tetraphenylborates, picrates, hydroxides, and carbonates. Arsenocholine bromide (X=OH) was phosphorylated with concentrated phosphoric acid. The product was isolated as the barium salt. Treatment of the barium salt with sulfuric acid yielded trimethyl-2-(dihydrogen phosphato)ethylarsonium bromide. These substances were synthesized to serve as precursors for arsenic- containing phospholipids and as standards for the chromatographic identification of arsenocholines. The synthesized compounds were characterized by elemental analyses and ¹H and ¹³C NMR spectroscopy. The shifts of the arsenic compounds were compared with those of the corresponding nitrogen compounds and found to be sufficiently different to be used for the identification of these compounds in their mixtures.     

Selected reactions on the o-aminonitrile system of substituted pyrroles

The synthesis of the difficult to obtain pyrrolo[2,3-d]pyrimidine-2,4-diamine (4) is reported. Furthermore, some unexpected reactions on the 2-aminopyrrole-3-carbonitrile system are described 15-17.     

Ein Klassifizierungsproblem für Riemannsche Flächen vom Geschlecht 1

Ohne Zusammenfassung