The reactions of evonine and neoevonine alkaloids obtained from Euonymus Sieboldiana blume

The reactions of evonine (1), neoevonine (2), alkaloids of Euonymus Sieboldiana Blume, and their derivatives are described. The structural proofs of some derivatives are included.     

Synthesis and Photochemistry of Novel 3,5-Diacetyl-1,4-dihydropyridines. II [1]

Summary. In continuation of previous work some novel 3,5-diacetyl-1,4-dihydropyridine derivatives were synthesized and their photochemical behavior was studied under oxygen and argon atmosphere. Oxidation of the dihydropyridine ring and formation of pyridine derivatives was the result of the reaction. The presence of oxygen affects not only on the rate of oxidation, but also the formation of some unidentified by-products was observed on irradiation under this atmosphere.     

香豆素衍生物在数种薄层基质上的室温磷光发射特性

考查了二十多种香豆素衍生物在国产ＭＮ－Ｐ型和ＭＮ－Ｃ型微晶纤维素膜，ＤＥＡＥ离子交换膜上的室温磷光发射特性，并与用滤纸作基质时的结果作了比较。在这些基质上，多数衍生物都能发射不同强度的ＲＴＰ信号，且在其ＲＴＰ特性间呈现，某些取代基效应。从发光稳定性和信背比考虑，ＭＮ－Ｃ型比ＭＮ－Ｐ型膜更适合于这些衍生物的ＲＴＰ发射。     

Benzyl isobornyl amines: a simple and practical class of NMR discriminating agents for effective chiral recognition of acids

The design and synthesis of a few simple N-benzyl derivatives of isobornyl amine is presented. The derivatives have been assessed as chiral solvating agents for effective discrimination of the signals of some acids in NMR analysis. The single crystal X-ray analysis of the salts of (R)-mandelic acid with two of the title derivatives help to understand the supramolecular interactions and assign the induced chemical shifts in ¹H NMR analysis. The title derivative is found to be suitable for quantitative determination of the enantiomeric excess of unknown enantiomeric purity as well as being efficient in resolving racemic mandelic acid.     

Synthesis and Antitumor Activity of 7-Substituted Derivatives of Homocamptothecin

Camptotecin is the parent of an important class of anticancer agents which, can selectively poison the ubiquitous nuclear enzyme topoisomerase. Water soluble camptothecin analogues such as topotecan and irinotecan are already approved for clinical uses in…     

Design and synthesis of two triazonine-carbaldehyde derivatives using several chemical tools

Several triazonine-carbaldehyde derivatives have been prepared using different protocols; however, some require special reagents and conditions. The aim of study involved the synthesis of two triazonine-carbaldehyde derivative using testosterone or OTBS-testosterone as chemical tool. Triazonine-carbaldehyde derivatives were prepared by a series of reactions that involve the following: (1) synthesis of two nitrobenzamide derivatives by reaction of testosterone or OTBS-testosterone with p-nitrobenzoyl azide using Copper(II) as catalyst; (2) reaction of the nitrobenzamides with ethylenediamine to form two triazonine derivatives using boric acid as catalyst; (3) preparation of hexynyl-triazonine derivatives by the reaction of two triazonines 6-chlorohex-1-yne in basic medium; (4) reaction of hexynyl-triazonine derivatives with benzaldehyde to form two triazoninol analogs; (5) preparation of triazoninynal derivatives through oxidation of triazoninol analogs with dimethyl sulfoxide; and (6) synthesis of triazonine-carbaldehyde derivatives by the reaction of triazoninynal derivatives with hexyne-1 using Copper(II) as catalyst. The chemical structure of compounds was determined by spectroscopic and spectrometric methods. In conclusion, in this work were prepared two triazoninone derivatives using several chemical techniques, which are simple procedures and easy to handle.     

Theoretical study of mono- and dithiocarbazic acid derivatives

The patterns of charge distribution in a series of derivatives of thiocarbazic acid are studied by means of several theoretical LCAO-MO methods: ab initio minimal basis-set, CNDO/2, INDO and EHT. Correlations are made between the electronic structures obtained from the calculations, the nature of the different substituents and some experimental IR, X-ray and XPS results.     

Boronnitrogen compounds : LXXXIX. New boron derivatives of pyrazole and imidazole

New monomeric N-borylated pyrazole and imidazole derivatives have been synthesized and some of their characteristic features have been explored. The suggested structures are supported by spectroscopic data.     

Electron density distribution in ferrocene analogues of stilbene. Interaction of substituents and molecular groups in ferrocene derivatives

Two techniques, ¹³C NMR and cyclic voltammetry, are utilized to determine the change of electron density distribution caused by substituents in ferrocene analogues of stilbene. The interactions of substituents and some molecular groups in four series of ferrocene derivatives is discussed and the transmission coefficients of these groups are presented.     

Inorgranic Reaction Mechanisms,Volume 3 (A Specialist Periodical Report of the Chemical Society,London), J. Burgess,Senior Editor,The Chemical Society,London, 1974, xvii + 500 pages, ß14.00.

A polyphosphite obtained from poly(methallyl alcohol), when treated with rhodium(I) derivatives, affords soluble and insoluble complexes, some of which are hydrogenation catalysts for olefins in toluene suspension.     

Sels de cobalticinium : II. Proprietes spectroscopiques et polarographiques de quelques derives du cobalticinium

The spectroscopic and polarographic behaviour of some cobalticinium derivatives have been studied. Due to their positive charge these compounds exhibit particular characteristics in comparison with ferrocene derivatives. They give two successive cathodic waves on a dropping mercury electrode. The first corresponds to the formation of cobaltocene whereas the second represents the reduction of the latter compound to give cobaltocene anion.     

Synthetic and conformational aspects of trimethylammonium-methyl substituted 2-oxazolines as potential cholinergics

The effects of some structural features on the cholinergic activity of 2-oxazoline derivatives has been investigated. Improved synthetic approaches to the 2-oxazoline ring system are developed, and several new fluorinated 2-oxazolines are described. The extensive NMR data give insight into the rotameric behaviour of the substituents.     

Analysis of heterocyclic aromatic amines in foods by gas chromatography-mass spectrometry as their tert.-butyldimethylsilyl derivatives

A derivatization method for the analysis of 12 heterocyclic aromatic amines (HAs) in food, by gas chromatography-electron impact mass spectrometry, was developed. The amines are derivatized in a one-step reaction with N-methyl-N-(tert.-butyldimethylsilyl)trifluoroacetamide. The derivatives are characterized by easy-to-interpret mass spectra due to the prominent ion [M-57]+ by loss of a tert.-butyldimethylsilyl group, allowing quantification in the selected-ion monitoring mode at the picogram level. The effect of temperature, time, and reagents on the formation of the derivatives was monitored in detail. Quality parameters were evaluated in the optimum working conditions. This derivatization method is not applicable to the pyridoimidazoles Glu-P-1 and Glu-P-2 and to the beta-carboline harman due to incompletely derivatization. The instability of the imidazolquinoline and imidazoquinoxaline derivatives, requiring their injection on the same working day, is a further drawback. This simple, rapid and accurate derivatization procedure is suitable for routine analysis, as illustrated by the analysis of some common foods.     

Properties and separation method of enantiomers of the mono- and bis-substituted derivatives of 3,3′,4,4′-tetramethyl-1,1′-diphosphaferrocene: structural analysis using X-ray diffraction and circular dichroism

This work expands on the recent separation of the enantiomers of the C₂-symmetrical bis-substituted derivatives of 1,1′-diphosphaferrocene. The effective separation of mono-substituted 1,1′-diphosphaferrocenes by the proposed method is demonstrated. The absolute configuration of the three separated components was established using X-ray diffraction. Circular dichroism spectra were collected for all of the separated compounds. The spectrum of each compound shows a characteristic curve, and the curves for the enantiomers are symmetrical. We also show that the correct absolute configuration for similar species can be assigned on the basis of the obtained data. We propose an explanation for the abnormal ¹H NMR spectra of phospholyl protons in some derivatives of 1,1′-diphosphaferrocene. A density functional theory (DFT) study of the conformation, as well as circular dichroism and NMR spectra of the chosen species, is also presented.     

Epothilone B and its Derivatives as Novel Antitumor Drugs: Total and Partial Synthesis and Biological Evaluation

Summary.  Microtubule stabilizing natural products, as exemplified by paclitaxel (taxol^?), are being considered as novel drugs against malignant therapy resistent solid tumors. Among these compounds, epothilone B and some of its derivatives have emerged as particularly promising candidates for industrial development. The total and partial syntheses of these compounds are described in detail, and some of the most important recent results on their biological activity are discussed. Received December 3, 1999. Accepted December 6, 1999     

Synthesis of chiral aza-bis(oxazolines) derived from (+)-camphor

Two novel chiral structurally azabis(oxazoline) ligands were synthesized using (+)-camphor as the starting material. Each of the ligands was prepared through the corresponding aminoalcohols. The structures of some crystalline derivatives were unambiguously established by X-ray analysis.     

Studies of di[(phenyldimethylsilyl)methyl]-methyltin dithiophosphates

Thirteen derivatives of di[(phenyldimethylsilyl)methyl]methyltin dithiophosphates have been synthesized and characterized by the elemental analysis, IR, 1H, 13C,119Sn NMR and MS. The results show that they are four-coordinated. The preliminary bioassay reveals that they have good acaricidal activity and some of them have insecticidal, herbicidal activities at the same time.     

Antimicrobial Activity and Structural Study of Disubstituted Thiourea Derivatives

Summary. The antimicrobial activity of six N-phenyl- and fourteen N-benzoylthiourea derivatives were evaluated from their Minimal Inhibitory Concentration (MIC) values using the microdilution procedure against ten microorganisms. Most of the compounds exhibited selective activity against fungi and Gram-positive bacteria, which were very effectively inhibited by some of the tested thioureas. Additionally, SAR considerations and four novel X-ray diffraction structures of N-benzoylthioureas are included.     

Synthesis and Stereochemistry of Novel Dibrominated 1,5-Dioxaspiro[5.5]undecane Derivatives

Summary.  The synthesis and stereochemistry of new dibrominated spiro-1,3-dioxane derivatives are reported. Investigations by means of NMR methods and single crystal X-ray diffraction for two compounds revealed the high regio- and diastereoselectivity of the bromination reaction of some new spiro-1,3-dioxanes and the asymmetric induction of the chiral carbon atom located in the spiro skeleton. Received July 13, 1999. Accepted October 21, 1999     

Synthesis and antiinflammatory activity of some pyrimidines and thienopyrimidines using 1-(2-Benzo[d][1,3]dioxol-5-yl)vinyl)-4-mercapto-6-methylpyrimidine-5-yl)ethan-2-one as a starting material

In continuation to our search for new heterocyclic systems based antiinflammatories, the suggestion and synthesis of some pyrimidines, thienopyrimidines, and their derivatives, were herein realized. The pharmacological screening showed that many of these compounds have good antiinflammatory activity. The structure assignments of the new compounds are based on chemical and spectroscopic evidence. The detailed synthesis, spectroscopic data, and pharmacological properties are reported. Correspondence: Abd El-Galil Elsayed Amr, National Research Center, Organic Chemistry Department, Cairo, Dokki, Egypt.