Antioxidant Study and Assignments of NMR Spectral Data for 3′,4′,7-Trihydroxyflavanone 3′,7-Di-O-β-D-glucopyranoside (Butrin) and Its Hydrolyzed Product

The NMR spectral data including high resolution ¹H, ¹³C and 2D NMR for butrin, 3,4,7-trihydroxyflavanone 3,7-di-O--D-glucopyranoside, isolated from flowers of Butea monosperma, are reported here for the first time. Butrin was hydrolyzed using b-glucosidase to butin in high yield. They were subjected to free radical scavenging test using 2,2-diphenyl-1-picrylhydrazyl (DPPH) spectrophotometric assay. At a dose of 4 × 10^-8 mol of tested compounds, the percentage of reduced DPPH for butin was 14.5% while no reduction was observed for butrin (0%).     

“Blue silver”: transformation of clusters and metal coagulation

The formation and transformations of blue silver ( _max 700 nm) during -irradiation of a weakly alkaline (pH 9) aqueous solution containing AgClO₄, polyacrylic acid (PAA), and isopropanol were studied. We believe that blue silver is a linear silver cluster stabilized on a polymeric molecule. During radiation-chemical reduction the cluster is transformed into new clusters ( _max = 365 and 460 nm). When all of the Ag⁺ ions present in the solution have been reduced, clusters coalesce and a new phase,i.e., colloidal silver particles, forms. The mechanism of the radiation-chemical transformations is discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 35–37, January, 1995.     

Photochemical addition of diethyl ether to β,β,β',β'-tetrakis(trifluoromethyl)divinyl ether

The 1:1 adducts of diethyl and ,,','-tetrakis(trifluoromethyl)divinyl ether (1),i.e., 3,5-(ee)-bis[2,2,2-trifluoro-1-(trifluoromethyl)ethyl]-2,6-dimethyl-1,4-dioxane (2) (3 isomers) and 4-ethoxy-1,1,1-trifluoro-2-trifluoromethyl-3-[3,3,3-trifluoro-2(trifluoromethyl)propenyloxy]pentane (3), have been obtained by UV-irradiation of a solution of divinyl ether1 in diethyl ether. The X-ray structural investigation of the all-(e)-isomer of dioxane (2) has been carried out.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 85–88, January, 1994.     

Studies of the energy spectrum of α, ω- substituted polymethine chains. II. Polymethine chains with odd number of methine groups

The analysis of the experimental data for the energy of the longest wavelength optical transitions _n,opt of substituted polymethines X (CH)_2n+1 X shows that in the asymptotic case (n) _,opt does not tend to zero, as it follows from the empirically established correlations, but has a finite, non-zero value. It is shown that the energy gap of odd polymethines is the same as that of the even polymethines - the polyenes (E 2 eV). The substituents (X N, O, B) are responsible for the appearance of levels in the gap. These, depending on the substituent character, are vacant (X B) or occupied (X N, O). The transition from or to such a level determines the longest wavelength optical transition energy of polymethines.     

Charge-transfer complexes betweenp-toluidine and iodine in solution: A kinetic study

The kinetics of charge-transfer interaction betweenp-toluidine and iodine in methylene chloride was investigated in depth. Thethermal process of formation of theinner complex was found to proceed to an equilibrium. Thephotochemical process follows a different reaction coordinate, going through the formation of an exciplex between the excitedouter complex and the amine ground state. In both cases the same ionic complex (Am ₂I⁺I ₃ ^– , whereAm stands forp-toluidine) was detected as the final product.

---

Kinetische Untersuchung der Charge-Transfer-Komplexe zwischenp-Toluidin und Jod

Zusammenfassung Die Kinetik der Charge-Transfer-Wechselwirkung zwischenp-Toluidin und Jod in Methylenchlorid wurde ausführlich untersucht. Derthermische Prozeß, der zur Bildung desinner-Komplexes führt, geht bis zu einem Gleichgewicht. Derphotochemische Prozeß folgt einer unterschiedlichen Reaktionskoordinate und verläuft über die Bildung eines Exziplexes zwischen dem angeregtenouter-Komplex und dem Amin im Grundzustand. In beiden Fällen wurde derselbe ionische Komplex (Am ₂I⁺I ₃ ^– , wobeiAm fürp-Toluidin steht) als Endprodukt festgestellt.

     

Reaction of aminals of conjugated unsaturated ω-dimethylaminoaldehydes with 1,2-, 1,3-, 1,4-, 1,5-, and 1,6-diketones

The condensation of aminals of -dimethylaminoacrolein and 5-dimethylaminopenta-2,4-dienal with cyclic and acyclic 1,2-, 1,3-, 1,4-, 1,5-, and 1,6-diketones was studied. A series of previously unknown bis(,-dimethylaminopolyenyl)diketones was synthesized; their structures were established by means of¹H and¹³C NMR spectroscopies. The electron absorption spectra were employed to study the mutual influence of -aminopolyene chromophores separated by two C=O groups.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1235–1241, July, 1993.     

peri-Naphthylenediamines. 38. Naphthalene and acenaphthene “proton sponges” with +M substituents in ortho positions with respect to peri-dimethylamino groups

Previously unknown 4,5,6,7-tetrakis(dimethylamino)acenaphthene, which is the first acenaphthene derivative containing four vicinal dialkylamino groups, was synthesized based on 5,6-bis(dimethylamino)-4,7-dinitroacenaphthene. The total synthesis of 1,2,7,8-tetrakis(dimethylamino)naphthalene was carried out starting from 3,6-dinitronaphthalic anhydride. Other proton sponges of this type, viz., 1,7,8-tris(dimethylamino)-2-methoxy- and 1,8-bis(dimethylamino)-2,7-dipiperidinonaphthalenes, were prepared by the nucleophilic substitution in 2,7-dimethoxy-1,8-dinitronaphthalene. In solutions, 1,2,7,8-tetrakis(dimethylamino)naphthalene and its analogs can form di- and trications in the presence of acids. The basicity constants pK _a ¹ of the compounds measured in DMSO depend in a complex way on their structures but correlate with the basicity index B, which is determined by changes in the chemical shifts _H after the addition of the first proton. Due to low C-nucleophilicity of ortho-disubstituted proton sponges in combination with high basicity, these compounds hold considerable promise as reagents in organic synthesis.     

Disordered Crystal Structure of 4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacozane perchlorate

Crystals of the ionic complex (salt) of 4,7,13,16,21,24hexaoxa 1,10diazabicyclo[8.8.8]hexacozane perchlorate, [H₂(Crypt2.2.2)]²⁺ · 2ClO₄ ^-, were synthesized and studied by Xray structural analysis: space group C2/c, a = 20.198(3), b = 10.119(2), c = 12.938(2), = 90.97(1)°, Z = 4, 3030 measured independent reflections, R = 0.067. In these crystals, all atoms of the 2.2.2 dication are disordered over two positions with occupancies of 0.518(4) and 0.482(4). Two conformations of the disordered 2.2.2 dication are such that two H atoms at two nodal N atoms point to its cavity.     

Synthesis and thermal decomposition of 3-aroyl-4-aryl-2-pyrazolines

Summary 3-Aroyl-4-aryl-2-pyrazolines (21–40) have been synthesized by the reaction of ,-unsaturated ketones (1–20) with diazomethane. These 2-pyrazolines gave -methyl-,-unsaturated ketones (41–46) on thermal denitrogenation.Dedicated to Prof. Dr.F. Sauter on the occasion of his 65^th birthday     

Kinetics and mechanism of the hydrolysis of sodium carboxymethylcellulose (Na-CMC) by a cellulase complex

TheSomogyi-Nelson colorimetric method is applied in a new manner more suitable for evaluating the kinetics of the enzyme hydrolysis of sodium carboxymethylcellulose (Na-CMC) catalyzed by the cellulase complex. By means of selective inhibition of a chosen enzyme from the cellulase complex it became possible to trace the effect of the other enzymes included in its composition.

---

Kinetik und Mechanismus der Hydrolyse von Natriumcarboxymethylcellulose (Na-CMC) durch einen Cellulase-Komplex

Zusammenfassung Die kolorimetrische Methode nachSomogyi undNelson wird nach einem neuen Verfahren zur Verfolgung der Kinetik der hydrolytischen Spaltung von Natriumcarboxymethylcellulose (Na-CMC), katalysiert durch den Cellulase-Komplex, angewandt. Durch selektive Inhibierung eines bestimmten Enzyms des Cellulase-Komplexes kann man die Wirkung der anderen zu seiner gesamten Zusammensetzung gehörenden Enzyme verfolgen.

---

Symbols Used E enzyme (E—cellulase;E—exo-cellobiohydrolase;E—-glucosidase) - [E] _w weight concentration of enzymeE - S substrate (Na-CMC—sodium carboxymethylcellulose) - [S]₀ weight concentration of substrateS - I inhibitor (I—lactose;I—calcium chloride;I—condurrite-B-epoxide) - P product (P—oligosaccharides;P—cellobiose;P—D-glucose) - P end product (K , K , K ) - DP degree of polymerization - DS degree of substitution - ES enzyme-substrate complex (E S, E S, E S) - EP enzyme-product complex (E P, E P) - EI enzyme-inhibitor complex (E I, E I, E I) - M _s molecular mass of substrateS - K _s substrate constant (K _s , K _s , K _s ) - K _I inhibitor constant (K _I , K _I , K _I ) - K _m Michaelis-Menten constant - k ₊₁,k ₊₂ (k ₊₂ ,k ₊₂ ,k ₊₂ ) forward rate constants - k _–1 reverse rate constant - ₀ initial rate of reaction - V maximal reaction rate - A change in absorbance - molar absorption coefficient - wavelength Herrn Prof. Dr.Hans Tuppy zum 60. Geburtstag herzlichst gewidmet.     

Crystal and Molecular Structure of Cu(II) Bis-(2-methoxy-2,6-dimethyl-3-imino-5-heptanonate)

A new compound from the series of alkoxyketoiminates, Cu(II) bis-(2-methoxy-2,6-dimethyl-3-imino-5-heptanonate), has been synthesized and studied by X-ray crystallography. Crystal data for CuO₄N₂C₂₀H₃₆: a=10.154(1), b=9.921(1), c=11.684(2) , =96.17(1)°, space group P2₁/c, Z=2, dcalc =1.226 g/cm³, R=0.037. The structure is molecular and built from isolated trans-complexes. The copper atom has a plane square environment of two oxygen atoms (Cu–O 1.93 ) and two nitrogen atoms (Cu–N 1.90 ). The O–Cu–N chelate angle is 91.7°. The complex has an intramolecular hydrogen bond, N–H...O 2.16 , involving the alkoxy oxygen atom. The molecular packing in the crystal is close to that of copper(II) dipivaloylmethanate. The calculated van der Waals intermolecular interaction energies and thermogravimetric characteristics of the complexes are compared.     

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.     

Synthesis of β‐Chlorinated Macrocyclic [Au(C14H20N4Cl2)]X (X = AuCl2, ClO4, AuCl4) Gold(III) Complexes. Crystal and Molecular Structures of [Au(C14H20N4Cl2)]ClO4

A squareplanar [AuL₂]⁺ gold(III) complex [L₂ = 6.13dichloro5,7,12,14tetramethyl1,4,8,11tetraaza4,6,11,13tetraenato(2-)] containing two chlorine atoms in the position of the ligand hexacyclic ring was first synthesized by the reaction of the [AuL₁]⁺ tetraiminate complex [L₁ = 5,7,12,14tetramethyl1,4,8,11tetraaza4,6,11,13tetraenato(2-)] with HAuCl₄ in an acetone – DMFA solution. The complex was isolated in the form of dichloroaurite (I), perchlorate (II), and tetrachloroaurate (III). Compounds I–III were studied by elemental and Xray diffraction analyses and IR and NMR spectroscopies. Single crystals of [AuL₂]ClO₄ were obtained, and the crystal structure of this compound was determined from Xray diffraction patterns. The crystals are monoclinic: a = 10.147(2), b = 7.260(1), c = 12.519(2), = 96.70(1)°, V = 915.9(3)³, Z = 2, space group P2/c, d_calc = 2.218, d_meas = 2.209 g/cm³ The crystal structure is built of nearly planar [Au(C₁₄H₂₀N₄Cl₂)]⁺ cations and [ClO₄]^- anions. Introduction of chlorine atoms into the positions of the hexacyclic rings of the tetraazamacrocycle hardly changes the lengths of the delocalized C N and C C bonds.     

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).

---

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).

     

β,β-Dinitro derivatives ofN-alkyl-N′-alkoxydiazene-N-oxides

Methods of synthesis ofN-alkyl-N-alkoxydiazene-N-oxides containing a carbonyl group in the -position of alkyl or alkoxy radicals were developed. ,-Dinitro derivatives ofN-alkyl-N-alkoxydiazene-N-oxides were synthesized for the first timevia nitration of oximes obtained from the ketones.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1534–1538, August, 1995.     

Microstructure and Chemical Bonding in Silicon Carbonitride Films Synthesized by Plasma Enhanced Chemical Vapor Deposition

Silicon carbonitride films were synthesized by plasma enhanced chemical vapor deposition using silyl derivatives of asymmetric dimethylhydrazine, (CH₃)₂HSiNHN(CH₃)₂ and (CH₃)₂Si[NHN(CH₃)₂]₂, as molecular precursors. The film material consists of an amorphous matrix with nanocrystalline inclusions. Indexing of synchrotron radiation Xray diffraction patterns suggests that the structure of the nanocrystals is tetragonal with lattice parameters a = 9.6 and c = 6.4. Xray photoelectron spectra indicate that Si—N and C—N sp ³ hybrid bonds are predominant. The absence of G or Dmodes in Raman spectra, which are otherwise typical of structures possessing sp ² bonding, provides further support for the tetragonal structure of the nanocrystals.     

Experience of σπ-correlations of carbanion reactions with electrophilic reagents

The problem of the possibility of applying ap-correlation analysis by the three sigmas' system to carbanion reactions with electrophilic reagents was considered. In particular the alkylation as well as Wittig and Homer olefination reactions were discussed. It was shown that the condition for the application of correlation analysis to such reactions is the constancy of the Brönsted's parameter connected with steric and reorganization factors of the substrates and solvents. Perfect correlations were observed when this condition was met.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 634–639, March, 1996.     

Reaction of dibenzylphosphine oxide with α,β-unsaturated O-methyloximes

The reaction of dibenzylphosphine oxide with O-methyloximes of some ,-unsaturated ketones results in the phosphorylation at the -carbon atom to form methoxyiminophosphine oxides, whereas the reaction of dibenzylphosphine oxide with O-methyloximes of ,-unsaturated aldehydes affords aminodihydrophosphole oxides.     

peri-Naphthylenediamines. 31. Study of interconversions of 2,3-dihydroperimidines and 1,8-bis(dialkylamino)naphthalenes. Convenient synthesis of 1,2,2,3-tetramethyl-2,3-dihydroperimidine and a monoisopropyl analog of the “proton sponge”

Efficient procedures were developed for the two-step synthesis of 1,2,2,3-tetramethyl-2,3-dihydroperimidines and for the one-step synthesis of 1,3-dimethyl-2,3-dihydroperimidines starting from 1,8-diaminonaphthalenes. New possibilities of the use of 2,3-dihydroperimidinium salts in the synthesis of 1,8-bis(dialkylamino)naphthalenes (proton sponges) containing the N-isopropyl group along with the N-methyl groups were demonstrated. The 1,1,2,2,3-pentamethyl-2,3-dihydroperimidinium cation exists in the acyclic iminium form responsible for its high reactivity.     

The conformational preferences of γ-lactam and its role in constraining peptide structure

Summary The conformational constraints imposed by -lactams in peptides have been studied using valence force field energy calculations and flexible geometry maps. It has been found that while cyclisation restrains the of the lactam, non-bonded interactions contribute to the constraints on of the lactam. The -lactam also affects the (,) of the residue after it in a peptide sequence. For an l-lactam, the ring geometry restricts to about-120°, and has two minima, the lowest energy around-140° and a higher minimum (5 kcal/mol higher) at 60°, making an l--lactam more favourably accommodated in a near extended conformation than in position 2 of a type II -turn. The energy of the +60° minimum can be lowered substantially until it is more favoured than the-140° minimum by progressive substitution of bulkier groups on the amide N of the l--lactam. The (,) maps of the residue succeeding a -lactam show subtle differences from those of standard N-methylated residues. The dependence of the constraints on the chirality of -lactams and N-substituted -lactams, in terms of the formation of secondary structures like -turns is discussed and the comparison of the theoretical conformations with experimental results is highlighted.