Synthesis of 2β, 3β, 14α-trihydroxy-Δ4,7-6-ketosteroids and their derivatives

A scheme using -sitosterol as an example for synthesizing 2, 3, 14-trihydroxy-^4,7-6-ketosteroids and their derivatives from 3-hydroxy-⁵-steroids was developed.Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, 220141, Belarus, Minsk, ul, akad. Kuprevicha, 5/2. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 244–248, May–June, 2000.     

Acid association quotients of bis-tris in aqueous sodium chloride media to 125°C

The ionic strength and temperature dependencies of the molal acid association quotients of 2,2-Bis(hydroxymethyl)-2,2,2-nitrilotriethanol (also abbreviated as bis-tris) were determined potentiometrically in a concentration cell fitted with hydrogen electrodes. The emf was recorded for equimolal bis-tris/bis- trisHCl buffer solutions from 5 to 125°C at approximately 25°C intervals, and at nine ionic strengths from 0.05 to 5.0m (NaCl). The molal association quotients, combined with infinite dilution values from the literature, are described precisely by a seven parameter equation which yielded the following thermodynamic quantities at infinite dilution and 25°C: logK=6.481±0.003, H ^o =–28.5±0.2 kJ-mol ^–1 , S ^o =28.5±0.8 J-K ^–1 -mol ^–1 , and C _P ^o =–22±5 J-K ^–1 -mol ^–1 . The equation incorporates a simple three term expression for logK, but requires four terms to describe the rather complex ionic strength dependence despite the reaction being isocoulombic. The molal association quotients from this study and the literature were also subjected to the Pitzer ion interaction treatment.     

Synthesis of stable oxazolidine nitroxyl radicals with methoxy groups at the α-carbon atoms to the radical site

The condensation of -hydroxyaminoalcohols with aldehydes and acetone gave 3-hydroxyoxazolidines and tautomeric N-(2-hydroxyethyl)--arylnitrones, whose oxidation by PbO₂ in methanol leads to stable oxazolidine nitroxyl radicals with methoxy groups at C² and C⁴.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk 630090. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 966–973, April, 1992.     

Synthesis of (22E,24R)-5a-ergosta-2,7,22-trien-6-one

The synthesis of the 5a-hydroxy-2,7,22-trien-6-one (3) has been achieved by the mesylation of ergosterol (1a) and oxidation of the resulting mesylate (1b) with chronic acid to 3,5a-dihydroxy-7,22-dien-6-one 3-mesylate, followed by elimination.Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, 220141, Minsk, ul. Akad. Kuprevicha. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 100–102, January–February, 1999.     

Synthesis of 2′,3′-dideoxynucleosides from 5-alkoxymethyluracils

Summary A modified synthesis of protected 2,3-dideoxyribose5 starting fromL-glutamic acid (1) is described. Reaction of5 with silylated 5-hydroxymethyluracil7 a and 5-alkoxymethyluracils7 b–e in the presence of trimethylsilyl triflate afforded an anomeric mixture of 2,3-dideoxyuridine derivatives8 a–e and9 a–e. Deprotection with methanolic ammonia and separation by chromatography gave the corresponding nucleosides10 a–e and11 a–e. Treatment of9 b–e with tri(1H-1,2,4-triazol-1-yl)phosphine oxide and subsequent reaction of12 b–e with ammonia in dioxane afforded the cytosine derivatives13 b–e which on treatment with methanolic ammonia gave the corresponding 2,3-dideoxycytidine derivatives14 b–e and15 b–e. In contrast with the parent compounds, these alkoxymethyl derivatives had no appreciable activity against human immunodeficiency virus (HIV-1).

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Synthese von 2,3-Dideoxynucleosiden aus 5-Alkoxymethyluracilen

Zusammenfassung Ausgehend vonL-Glutaminsäure (1) wird eine modifizierte Synthese von geschützter 2,3-Dideoxyribose (5) beschrieben. Reaktion von5 mit silyliertem 5-Alkoxymethyluracilen7 b–e in Gegenwart von Trimethylsilyltriflat ergab anomere Mischungen der 2,3-Dideoxyuridinderivate8 a–e und9 a–e. Abspaltung der Schutzgruppe mit methanolischen Ammoniak und chromatographische Trennung ergab die entsprechenden Nucleoside10 a–e und11 a–e. Behandlung von9 b–e mit Tri(1H-1,2,4-triazol-1-yl)phosphinoxid und nachfolgende Reaktion von12 b–e mit Ammoniak in Dioxan ergab die Cytosinderivate13 b–e, welche nach Behandlung mit methanolischem Ammoniak die entsprechenden 2,3-Dideoxycytidinderivate14 b–e und15 b–e ergaben. Im Gegensatz zur Stammverbindung hatten diese Alkoxymethylderivate keine nennenswerte Wirksamkeit gegen den menschlichen Immunschwächevirus (HIV-1).

     

Triterpene Glycosides of Astragalus and Their Genins. LXI. Occurrence of Cycloartane 6-O-Monodesmosides

Cyclosiversigenin 6-O--L-rhamnopyranoside and 6-O--D-glucopyranoside were isolated fromAstragalus coluteocarpusBoiss. (Leguminosae) andAstragalus dissectusB. Fedtsch. et N. Ivanova, respectively. Cyclosiversigenin 5-O--L-rhamnopyranoside was shown to be an artifact forAstragalus coluteocarpus.Thus, the cyclosiversigenin 6-O--D-glucopyranoside that was isolated from certainAstragalusspecies is hypothesized also to be an artifact. Glycosylation of the 6 -hydroxyl group of cycloartanes by D-glucose and D-xylose, in contrast with other substituents, does not change the low-field position of the PMR signal of the 4-CH ₃ group (1.65 2.01 ppm) that is caused by the influence of deuteropyridine directly on the 6 -hydroxyl. Obviously one of the hydroxyls of the -D-glucopyranoside or -D-xylopyranoside residues has the same effect in this instance.     

Intramolecular Y←O (Y = N,P, As,Sb, Bi) coordination in organopnictogen compounds: an ab initio and DFT study

The molecular structure and rearrangements of -pnictogenovinylaldehydes and 1,6-dioxa-6a⁵-pnictapentalenes (Pn = N, P, As, Sb, and Bi) were studied using the ab initio and DFT approach. According to calculations, the quasi-cyclic conformation of -pnictogenovinylaldehyde molecules is much more stable than their free of strain, trans-s-trans conformation. This stabilization is achieved due to the formation of a rather strong secondary PnO bond of the hypervalent type. Bicyclic structures of 1,6-dioxa-6a⁵-pnictapentalenes (Y = P, As) with the three-center, four-electron hypervalent O—Y—O bonds are more energetically favorable than isomeric sterically unstrained monocyclic structures. The strength of the intramolecular coordination bonds (R)YO in -pnictogenovinylaldehydes and of the hypervalent bonds O—Y(R)—O in 1,6-dioxa-6a⁵-pnictapentalenes increases in the order Y = N, P, As, Sb, and Bi and with an increase in the electronegativity of the substituent R = H, Cl, and F. In contrast to their chalcogen-containing analogs, the above-mentioned quasi-cyclic and bicyclic structures of organopnictogen compounds possess low aromatic character.     

Synthesis of Side Chain Substituted 3-Butylisocoumarins and Absolute Configurations of Natural Isocoumarins from <Emphasis Type="Italic">Artemisia dracunculus</Emphasis>

Summary. A series of 3-hydroxy- and 3-bromobutyl-substituted isocoumarins was synthesized. The absolute configurations of three isocoumarin derivatives from Artemisia dracunculus, namely (–)-epoxyartemidin, (–)-2-methoxydihydroartemidin, and (+)-3-hydroxyartemidin were determined by chemical means via derivatization, kinetic racemate resolution (Horeau method), and comparison of the circular dichroism (CD) spectra.DeceasedReceived March 17, 2003; accepted March 19, 2003 Published online August 18, 2003     

2-[2′-(6′-Methyl-benzothiazolyl)azo]-5-dimethylaminobenzoic acid as a new reagent for rapid spectrophotometric determination of copper

2-[2-(6-methyl-benzothiazolyl)azo]-5-dimethylaminobenzoic acid (MBTAMB) has been synthesized and employed as a new reagent for the spectrophotometric determination of copper(II). A blue complex is formed from MBTAMB and Cu(II) in the range of pH 2.0–5.0 in aqueous ethanol. The composition of the complex is Cu(II) MBTAMB=1 1. The maximum absorption of the complex is at 660 nm, its apparent molar absorptivity is 7.0 × 10⁴ 1· mole^–1 · cm^–1. Beer's law is obeyed for copper in the range of 0–0.72 g/ml. The method has been used for the determination of micro amounts of copper in aluminium alloy. The proposed method is simple, rapid and accurate.     

Ritter reactions. VIII. Inclusion compounds formed betweenN-(5H-Dibenzo[a,d]cycloheptyl)acetamides and dioxane

5H-Dibenzo[a, d]cyclohepten-5-ol2 and its saturated analogue4 undergo Ritter reactions with acetonitrile and sulfuric acid to afford the acetamide derivatives3 or5 respectively. Both products form unstable inclusion compounds when crystallised from dioxane. The crystal structure of the dioxane compound of3 is reported. This material [(C₁₇H₁₅NO)·(C₄H₈O₂)₂,Pnma,a=9.616(1),b=23.280(2),c=10.298(1) Å,Z=4,R=0.054] has the amide molecules arranged in parallel chains by means of intermolecular –N–HO=C hydrogen bonds. The inclusion compound is stabilised by means of –C–HO-hydrogen bonds. Each dioxane molecule is involved in five such interactions to neighbouring molecules of3 and dioxane.Author for correspondence. Supplementary Data relating to this article are deposited with the British Library as supplementary publication No. SUP 82173 (5 pages).     

Volumetric Properties of Amino Acids and Hen-Egg White Lysozyme in Aqueous Triton X-100 at 298.15 K

The apparent molar volumes, V_,2, of glycine, alanine, -amino-n-butyric acid, valine, leucine, and lysine monohydrochloride have been determined in aqueous solutions of 0.05, 0.1, and 0.4 mol-kg^–1 Triton X-100 (TX-100), and the partial specific volume, v⁰, of hen-egg-white lysozyme in 0.4 mol-kg^–1 TX-100 by density measurements at 298.15 K. These data have been used to calculate the infinite dilution apparent molar volumes, V_2,m⁰, for the amino acids in aqueous TX-100 solutions and the standard partial molar volumes of transfer, _tr V_2,m⁰, of the amino acids from water to the aqueous surfactant solutions. The linear correlation of V_2,m⁰ for a homologous series of amino acids has been utilized to calculate the contribution of the charged end groups (NH₃⁺, COO^–), CH₂ group and other alkyl chains of the amino acids to V_2,m⁰. The results on _tr V_2,m⁰, of amino acids from water to aqueous TX-100 solutions have been interpreted in terms of ion–ion, ion–polar, hydrophilic–hydrophilic and hydrophobic–hydrophobic group interactions. For all the six amino acids studied, the values of _tr V_2,m⁰ from water to all the studied concentrations of aqueous TX-100 are small in spite of their different hydrophobic content, indicating an overall balance in interactions of zwitterionic/hydrophilic groups of amino acids with the hydrophilic groups of TX-100, and of hydrophobic and ionic/hydrophilic groups of the amino acids with hydrophobic groups of TX-100. Comparison of the interactions of the amino acids with nonionic, anionic and cationic surfactants has also been made and discussed. The partial specific volume of transfer of lysozyme from water to aqueous TX-100 solutions also indicates a balance of the hydrophobic and hydrophilic interactions in the protein–nonionic surfactant system.     

Binding constants of calcium and/or magnesium electrolytes and aggregation numbers in oil-in-water type microemulsions formed by an amphoteric surfactant

The effects of anti-symmetric electrolytes (CaCl₂, Ca(SCN)₂, MgCl₂, and/or Mg(SCN)₂) and pH on the phase behavior, the -potential, the hydrodynamic diameter and the surface charge density of an oil-inwater type (O/W-type) microemulsion formed in solutions of an amphoteric surfactant (N ,N -dimethyl-N -lauroyllysine, DMLL)/n-octane/1-pentanol/brine have been examined. The formation of the microemulsion in the presence of CaCl₂ and/or Ca(SCN)₂ is of Winsor-type with an increase in the concentration of 1-pentanol. Particularly, microemulsion is not formed by the addition of Ca(SCN)₂ in a pH region less than 2.6. The -potential and the surface charge density of the microemulsion in the presence of CaCl₂ decrease with an increase in pH and show slightly positive values in the isoelectric region (pH 5-7), while, in the presence of Ca(SCN)₂, the -potential and the surface charge density show negative values in the same region at which the net charge of DMLL molecules becomes almost zero. The hydrodynamic diameters in the presence of CaCl₂ show a maximum value around pH 2.5, whereas, in the presence of Ca(SCN)₂, the minimum value is around pH 5.5. Similar tendencies are recognized in results for the -potential, the hydrodynamic diameter and the surface charge density of the O/W-type microemulsion in the presence of MgCl₂ and Mg(SCN)₂. A new formula to estimate the binding constants (K) of Ca²⁺, Mg²⁺, Cl^–, and SCN^– to the hydrophilic groups in DMLL molecules and the adsorption density of DMLL molecules on the oil/water interface (N) in the presence of antisymmetric electrolytes has been derived.K for Ca²⁺, Mg²⁺, Cl^–, and SCN^– was found to beK _Ca=0.12M^–1,K _Mg=0.14 M^–1,K _Cl=0.0084±0.0016 M^–1, respectively.N for DMLL molecules in the presence of CaCl₂, Ca(SCN)₂, MgCl₂ and/or Mg(SCN)₂ was found to be 0.50 nm^–2, 0.38 nm^–2, 0.44 nm^–2, and 0.47 nm^–2, respectively; and the surfactant (DMLL) numbers per O/W-type microemulsion droplet change from a few hundreds to a few thousands with changing pH. The larger the hydrodynamic diameter of the O/W-type microemulsion, the greater the number of DMLL molecules adsorbed on the O/W-type microemulsion surfaces.     

Synthese von N-geschütztem Eledoisin (6–11)-Hexapeptid unter Verwendung von Proteasen als Biokatalysatoren

Papain and -chymotrypsin were used for the protease-catalyzed assembly ofBoc-protected eledoisin (6–11)-hexapeptide by (2+4)- and (3+3)-segment condensation, respectively, in aqueous-organic solvent systems. As C-components, chemically synthesizedBoc-protected peptide methyl esters were employed. The nucleophilic tetrapeptide amide was prepared by papain-catalyzed (2+2)-segment coupling, while theZ-protected C-terminal dipeptide amide could be obtained by -chymotrypsin- and thermolysin-catalyzed peptide bond formation. In addition, the influence of various reaction conditions, such as solvent composition, nucleophile concentration and reaction time, on the yield of theBoc-protected eledoisin (6–11)-hexapeptide was determined.

Abkürzungen: Es wurden die IUPAC/IUB-Regeln für Aminosäure- und Peptidderivate befolgt; vgl. Eur. J. Biochem.53, 1 (1975). Die verwendeten Aminosäuren hatten mit Ausnahme von GlycinL-Konfiguration.Boc=tetr-Butyloxycarbonyl-,Z=Benzyloxycarbonyl-,Ac=Acetyl-, –OMe=Methylester.     

All-Solid-State PVC Membrane Ag+-Selective Electrodes Based on Diaza-18-Crown-6 Compounds

Two diaza-crown ether compounds were synthesized and evaluated as Ag⁺-selective carriers in polyvinylchloride (PVC) membrane electrodes of solid-state type. The all-solid-state PVC membrane electrode based on N,N-Dibenzyl-dibenzo-diaza-18-crown-6 exhibited a super-Nernstian response (75±10mV per decade) over the concentration range of 1×10^–1 to 7×10^–6M of Ag⁺ ion and a detection limit of 3×10^–6M, at a wide range of pH (pH 4–7). The response time of the electrode was fast (less than 10s), and it can be used for three months without any significant deviation in potential. The proposed all-solid-state PVC membrane electrodes revealed high selectivity toward Ag⁺ ion with respect to alkali, alkaline earth, heavy and transition metal ions. A flow-through cell of all-solid-state PVC membrane Ag⁺-selective electrode based on N,N-Dibenzyl-dibenzo-diaza-18-crown-6 has also been prepared and applied for flow-injection analysis of Ag⁺ ion in solution.     

Synthesis of formyl derivatives of benzocrown ethers containing N,S, and O heteroatoms in the macrocycle

A method for the synthesis of 4-bromobenzodithia-15(18)-crown-5(6) and 4-bromobenzodiaza-15 (18)-crown-5(6) by condensation of 3,4-di(2-haloethoxy)bromobenzene with polyoxaalkanes containing terminal SH or NHMe groups was suggested. The method for the synthesis of formyl derivatives of benzocrowns containing N, S, and O heteroatoms in the macrocycle based on the metallation of appropriate bromo derivatives with BuⁿLi followed by treatment of the resulting organolithium intermediates with DMF was developed. Oximes and semicarbazones of benzaldehydes containing a crown ether fragment were obtained, and their transformation into the original aldehydes by treatment with KNO₂ in an acid medium was studied.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 121–128, January, 1995.This study was financially supported by the Russian Foundation for Basic Research (Grant No. 94-03-08-531) and the International Science Foundation (Grant M8Q000).     

Partial Molar Volumes of Transfer of Some Amino Acids from Water to Aqueous Glycerol Solutions at 25°C

Apparent molar volumes of glycine, DL--alanine, L-valine, L-leucine, and L-phenylalanine in 0.5, 1.0, 2.0, 3.5, and 5.0 m _B (mol-kg^–1) aqueous solutions of glycerol have been obtained from solution densities at 25°C using precise vibrating-tube digital densimeter. The estimated partial molar volumes at infinite dilution V ^o ₂ have been used to obtain the corresponding transfer volumes _tr V ₂ ^o from water to different glycerol–water mixtures. The transfer volumes are positive for glycine and DL--alanine, and both positive and negative for the other amino acids over the concentration range studied. Interaction coefficients have been obtained from McMillan–Mayer approach and the data have been interpreted in terms of solute–cosolute interactions.     

Synthesis of 4′4″(5″)-dibenzo-18-crown-6-disulfonic acid disalsolidinide,disalsolinide, and dianabasinide

New disulfamides of dibenzo-18-crown-6 with salsolidine, salsoline, and anabasine were prepared by condensation of the corresponding alkaloids with 4,4(5)-dibenzo-18-crown-6-disulfonyl chlorides.Presented at the 5th International Symposium on the Chemistry of Natural Compounds (Tashkent, Uzbekistan, May 20–23, 2003).Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 413–415, September–October, 2004.     

Reaction of pyridoxal 5′-phosphate with TRIS

Kinetic and equilibrium studies are presented on the reaction of pyridoxal 5-phosphate withTris. Upon raising thepH from 7.3 to 9.3 at 25°C, the second-order rate constant increases from 1.05 M^–1 s^–1 to 3.79 M^–1 s^–1, whereas the apparent dissociation constant varies from 2 to 8 mM. These results demonstrate the significance of this reaction whenTris buffer is used in studies of pyridoxal 5-phosphate-dependent enzymes.

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Reaktion von Pyridoxal-5-phosphat mit TRIS

Zusammenfassung Es werden Untersuchungen über die Kinetik und das Gleichgewicht der Reaktion von Pyridoxal-5-phosphat mitTRIS vorgelegt. Wenn derpH bei 25°C von 7,3 auf 9,3 erhöht wird, steigt die Geschwindigkeitskonstante zweiter Ordnung von 1,05 M^–1 s^–1 auf 3,79 M^–1 s^–1, während die scheinbare Dissoziationskonstante sich im Bereich von 2 bis 8 mM verändert. Die Ergebnisse zeigen, welche Bedeutung diese Reaktion für Untersuchungen von Pyridoxal-5-phosphat-abhängigen Enzymen bei Verwendung vonTRIS-Puffer hat.

     

Synthesis of an intercalated compound of montmorillonite and 6-polyamide

Natural montmorillonite, fractionated from bentonite produced in Yamagata, Japan, was ion-exchanged for NH ₃ ⁺ –(CH₂)₁₁–COOH, NH ₃ ⁺ –(CH₂)₅–COOH, Al³⁺, Cu²⁺, Mg²⁺, Co²⁺, Li⁺, K⁺ and H⁺. The mixtures of the ion-exchanged montmorillonite and -caprolactam were heated at 263°C in glass ampoules for various periods. The intercalated compounds before and after the heating were examined by X-ray powder diffraction, DSC and GPC. Although -caprolactam was not polymerized without montmorillonite, it was polymerized at 263°C in the presence of montmorillonite. The polymerization rate varied with the interlayer cations in the order of NH ₃ ⁺ –(CH₂)₁₁–COOH>Al³⁺>NH ₃ ⁺ –(CH₂)₅–COOH>H⁺>Cu²⁺>Mg²⁺>Co²⁺>Li⁺>K⁺. After heating at 263°C for 5 h, the mean number-average molecular weight was about 1.5×10⁴. Although the interlayer distance of NH ₃ ⁺ –(CH₂)₁₁–COOH type montmorillonite/-caprolactam compound increased from 2.85 nm to 4.90 nm by heating at temperatures above the melting point of -caprolactam, those of other compounds were not changed. After heating at 263°C, an intercalated compound of montmorillonite and 6-polyamide, whose interlayer distance was more than 10 nm, was obtained. It is concluded that montmorillonite acts as a Brönsted acid and initiates the open ring polymerization of -caprolactam and that the driving force of swelling is the polymerization energy.Presented at the Fourth International Symposium on Inclusion Phenomena and the Third International Symposium on Cyclodextrins, Lancaster, U.K., 20–25 July 1986.     

Polymorphism of Inclusion Complexes and Unsolvated Hosts. IV. Dimorphism of the Acetone Host–Guest Complex of Dianilinegossypol. Structures of the α- and β-Phase Complexes

Crystal structures of the - and -phase inclusion complexes of dianilinegossypol with acetone obtained at 20° and 30 °C, respectively, have been determined by X-ray structure analysis. Crystal data of the -phase complex are: C₄₂H₄₀O₆N₂2C₃H₆O, orthorhombic, space group Pccn, a = 29.501(9), b = 10.866(2), c = 13.756(3) Å, V = 4409(1) ų, Z = 4, D _x = 1.18 g cm^-3. The structure has been refined to a final R value of 0.117 for 1401 observed reflections. The host–guest ratio for the -phase complex is the same (1 : 2) and the crystals are monoclinic, space group C2/c, a = 28.352(6), b = 11.836(2), c = 13.196(1) Å, = 93.05(1)°, V = 4422(2) Å3, Z = 4, D _x =1.18 g cm^-3. The structure has been refined to a final R value of 0.077 for 1414 observed reflections.In both phases molecules of dianilinegossypol form hydrogen-bondedribbons by O(4)–-HO(3) H-bonds. Phases are determined by the same structural motif. In the -phase complex the cages are in the form of prisms but in the -phase clathrate they undergo a modification by shrinking in two directions and widening in one. Molecules of acetone are hydrogen bonded to the host molecules via aO(1)–-HO(G) bond and are accommodated in cavities for both complexes, i.e. both phases are cryptate-type inclusion complexes.Supplementary data relevant to this publicationhave been deposited with the British Library,No. SUP 82227 (24 pages).