Synthesis of some new derivatives of dithiene-and oxathienecarboxylic acids

Substituted anilides of 1,4-dithiene- and oxathienecarboxylic acids were synthesized. It was shown that the reaction of 3-phenyl-1,4-dithi-2-ene-2-carboxyl chloride with 2-aminopyridines, depending on the base used and the reaction conditions, leads to the formation of N-[3-phenyl-2-(1,4-dithi-2-en)ylcarbonyl]2-amino-pyridine and/or N,N-bis[3-phenyl-2-(1,4-dithi-2-en)-ylcarbonyl]pyridonimine. The data of IR, UV, and PME spectroscopy were used to confirm the structure of the synthesized compounds.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Science Center, Russian Academy of Sciences. Kazan 420083. Translated fro, Khimiya Geterotskiklicheskikh Soedinenii, No. 9, pp. 1191–1196, September, 1994. Original article submitted May 10, 1994.     

Synthesis of convalloside

The known natural diglycoside convalloside — strophanthidin 3-O-[4-O--d-glucopyranosyl--L-rhamnopyranoside] — has been synthesized. The synthesis was carried out by the Koenigs-Knorr method via the preparation as intermediates of convallatoxin and its 2,3-isopropylidene derivative. Selectivity of glycosylation was achieved by the preliminary protection of the two OH groups in the cardenolide L-rhamnoside (convallatoxin).All-Union Scientific Research Institute of Drug Chemistry and Technology, Khar'kov. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 383–386, May–June, 1988.     

Stereostructure of 2-ethynyl-substituted 2,4,4-trimethyl-1,3-dioxanes

It has been shown by PMR spectrometry and x-ray structure analysis that the six-membered 1,3-dioxane ring of 2-ethynyl-substituted 2,4,4-trimethyl-1,3-dioxanes, either in solution or in the solid state, exists in a nearly ideal chair conformation with an axial position of the ethynyl substituent. Kuban State Technological University, Krasnodar 350072, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 163–169, February, 1998.     

Structure of Lipid A from Pseudomonas corrugata by electrospray ionization quadrupole time-of-flight tandem mass spectrometry

The use of the electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-QTOFMS) technique for the structural determination of Lipid A from Pseudomonas corrugata is described. This technique appears to be more sensitive with respect to other commonly used tandem mass spectrometric approaches, and was very valuable in the structural determination of the highly heterogeneous Lipid A fractions. The Lipid A fraction consists mainly of a pentaacyl component in which 3-hydroxydecanoyl [10:0(3-OH)] and 3-hydroxydodecanoyl [12:0(3-OH)] are linked as primary acyl substituents to the classical bisphosphorylated beta-(1' --> 6)-linked D-glucosamine disaccharide. Secondary substitution of N-acyl fatty acids with dodecanoyl residues [12:0] and/or its 2-OH derivatives was also observed.     

Test ofBΣ-interaction potentials in Na 3P-rare gas systems from light scattering

The spectral dependences in Na-rare gas optical collisions $$Na3S + X + hv \to Na3P_J + X$$ have been used to study the long range interaction in Na 3P _J -X systems. For a test of available potentials the fine structure (fs) population ratio and theJ = 3/2 alignment were measured under single collision conditions by analyzing the fluorescence emitted after selective excitation of the molecularBΣ orAΠ states as function of the laser frequencyv. A comparison was made with quantum coupled channels (CC) calculations of thermally averaged spectral profiles using the potential data to be tested as input. In addition, model calculations were performed for a qualitative understanding of the role of the various nonadiabatic couplings involved and the trends in the spectral profiles by the corresponding molecular potentials. In NaAr and NaKr theBΣ-fs wings are seen to depend sensitively on the parameters of the potentials, in particular on the well depth? _ΣII of theBΣ-AΠ difference potentials which is comparable to the spin orbit interaction in these systems; the experimental profiles show, that the actual? _ΣII values are much smaller than those predicted by the model potentials of Düren. In NaKr also theBΣ-alignment wing depends sensitively on? _ΣII caused by a long-range parity dependent rotational coupling, as follows from the CC-analysis. The comparison with the experimental alignment confirms the result from theBΣ-fs wing regarding the actual? _ΣII value.     

cis- and trans-N-nitroso-2,4-diphenylazetidines

The synthesis of cis- and trans-2,4-diphenylazetidines as well as that of their N-nitroso derivatives is described. The “abnormal” reduction of the N-nitrosamines gives a cis-trans mixture of the expected 1,2-diphenylcyclopropanes. However, no stereochemical correlations could be made owing to the base-induced isomerization of the starting N-nitrosamines during the course of the reaction.     

ABSENCE OF OXYGEN-EVOLVING CAPACITY IN DARK-GROWN CHLORELLA: THE PHOTO ACTIVATION OF OXYGEN-EVOLVING CENTERS*

Abstract— Chlorella cells were cultured in darkness on glucose and examined for pigment composition, capacity to evolve oxygen, and capacity to photo-oxidize artificial electron donors to Photosystems II and I. Evidence was obtained which indicated that such cells lack oxygen-evolving centers and the Mn pool associated with such centers but possess fully active System II and I trapping centers. Brief illumination ( t _1/2˜ 2–3 min) of dark-grown cells resulted in incorporation of Mn into the O₂-evolving centers and the capacity to evolve O₂ (photo-activation). Kinetic data from flashing or continuous light showed that the photoactivation is a multi-quantum process involving several rate limitations and a photosensitive state of limited stability. Measurements of oxygen-yield oscillations indicated that throughout the photoactivation process each newly formed oxygen-yielding center was independent of its neighbors. It is concluded that photoactivation of the Mn-containing oxygen-yielding catalyst is a fundamental process in all photosynthetic oxygen-evolving tissue.     

Über in 11-Stellung amino-substituierte Dibenzo[b,f]-1, 4-thiazepine und -oxazepine. 9. Mitteilung über siebengliedrige Heterocyclen

Neuroleptics are found in the 11-amino substituted dibenzo[b,f]-1, 4-thiazepine and dibenzo[b,f]-1, 4-oxazepine series III. They may be synthesized by aminolysis of the iminochlorides VI and/or by Bischler-Napieralski ring closure of the urea II with POCl₃.     

A general method for the preparation of 4- and 6-azaindoles

Nitropyridines reacted with an excess of vinyl Grignard reagent to produce 4- or 6-azaindoles. Improved yields were obtained when a halogen atom was present at the position alpha to the nitrogen atom in the pyridine ring.     

Catalytic cathodic stripping voltammetry of oxidized glutathione at a hanging mercury drop electrode in the presence of nickel ion

Oxidized glutathione (GSSG) can be determined after previous accumulation on the HMDE at E > -0.2 V (vs. the Ag AgCl reference electrode). GSH is formed during the accumulation, possibly by a mercury-ion-assisted hydrolytic disproportionation of GSSG. In the subsequent cathodic scan GSH is released and catalyses the reduction of nickel ion, giving a peak located at -0.6 V. This enables the determination of GSSG by differential-pulse cathodic stripping voltammetry at pH 7.0 in the phosphate acetate or MOPS buffer containing 0.5-1.0 mM Ni(II). The detection limit is 10 nM. The calibration graph is linear even in the presence of small amounts of human serum albumin, HSA. However, HSA increases the detection limit (20 nM for 3 x 10(-4)% HSA). Acetyl-cysteine in small excess or Cu(II) present as reagent impurity do not interfere. Glutathione, cysteine and similar compounds, which accumulate as mercury salts and form stable nickel complexes, will interfere. The method is put forward as a novel alternative stripping voltammetric method to those involving accumulation and determination as mercury or copper salts and complexes, in the knowledge that it may have advantages in particular analytical situations. In particular the method discriminates against compounds which accumulate as mercury salts but which do not form stable nickel complexes.