Novel Synthesis of 2β,3β,20β-Triacetoxy-5 -pregnan-6-one

Pregnenolone (2) is used in a novel synthesis of 2,3,20-triacetoxy-6-ketosteroid (6), a key intermediate in the preparation of 20-hydroxyecdysone (1)     

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.     

X-ray diffraction studies on homologous thallium soaps below the temperature range of the neat phase 1. Calculation and comparison of the structure parameters of unit cells

The results of X-ray diffraction patterns of homologous thallium soaps TlC _n (n-8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 20 and 22) in dependence on the temperature showed that the structures of the phases below the temperature range of the liquid-crystalline neat phase (so called phase C₁, phase C₂, phase I, phase II) are crystalline-like, not liquid-crystalline.As function of the chain length of the fatty acid group, we found the following phase sequences to be a function of temperature: TlC₈: phase Ineat phase: TlC₉–Tl₁₄: phase C₂phase IIphase Ineat phase; TlC₁₅, TlC₁₆: phase C₁phase IIphase Ineat phase; TlC₁₇–TlC₂₂: phase C₁phase IIneat phase.From the X-ray patterns of the thallium soaps were calculated the lattice parameters and the unit cells of these homologues at various temperatures. The comparison between the lattice parameters of the homologues showed, surprisingly, that these parameters were independent of chain length and temperature. This X-ray data are the basis for the following development of structure models of the phase C₁, phase C₂, phase I, and phase II, including the neat phase (see Part 2).     

Enumeration of Kekulé structures for some coronoid hydrocarbons: “Waffles”

Summary Primitive coronoids of hexagonal symmetry (D _6h orC _6h ) are referred to as waffles. Some theorems about unbranched catacondensed benzenoids are presented and used to derive a general combinatorial formula for the number of Kekulé structures (K) for waffles. The symmetry-adapted method of fragmentation is employed. SeveralK formulas for special classes of waffles are also reported.

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Die Anzahl von Kekulé-Strukturen für einige aromatische Coronoid-Kohlenwasserstoffe: Waffel-Strukturen

Zusammenfassung Einfache Coronoide von hexagonaler Symmetrie (D _6h oderC ₆ h) werden als Waffel bezeichnet. Einige Theoreme bezüglich unverzweigter catakondensierter Benzenoide werden angegeben und zur Ableitung einer generellen Formel für die Anzahl von Kekulé-Strukturen (K) für Waffel benutzt. Es wird die symmetrie-adaptierte Methode zur Fragmentierung angewendet. Außerdem werden einigeK-Formeln für spezielle Klassen von Waffeln angegeben.

     

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.     

A new detection method for purines in thin-layer chromatography

Summary The separation of some purines by thin-layer chromatography, utilizing precoated plates with Silicagel R as stationary phase and the following mobile phases: i-butanol: methylethylketone: ammonium hydroxide 25%: water (40252015) and n-propanol: ammonium hydroxide 25%: water (80155) is reported.Visualisation of the spots has been achieved by spraying with aqueous 1% uranyl acetate and irradiating with UV both at 254 and 366 nm. The visual detection of a spot was 0.01 g.     

Inclusion Complexation of Carbaryl and β-Cyclodextrin in Solution and in the Solid State

This study was carried out with the aim ofinvestigating the interactions between-cyclodextrin and carbaryl, a carbamatepesticide, and their effect on some physico-chemicalproperties of carbaryl, such as aqueous solubility andlipophilicity. The interactions between carbaryl and-cyclodextrin were thoroughly investigated bothin solution and in the solid state. The effect of-cyclodextrin on the aqueous solubility ofcarbaryl was evaluated by the phase solubility method.The amount of carbaryl dissolved increased linearlywith the addition of -cyclodextrin according toan A_L type plot and without precipitation of thecomplex. The apparent stability constant of thecomplex was 289 ± 21 M^-1, assuming a 1 : 1stoichiometry; this value was confirmed by a methodbased on circular dichroism measurements.Equimolar carbaryl/-cyclodextrin solid systemswere prepared by physical-mixing and freeze-drying,and fully characterised by Differential ScanningCalorimetry, X-ray powder diffractometry and FourierTransform Infra-Red analysis. The results of the solidstate study demonstrated that the freeze-drying methodyields a system with a high degree of amorphisationand yields an inclusion complex.The dissolution profile of the pesticide was affectedby the physico-chemical properties of each solidsystem, the freeze-dried form dissolving more rapidly. However, the physical association of-cyclodextrin and carbaryl enhanced the aqueoussolubility of the insecticide as well.     

Inclusion of Ring A of Cholesterol Inside the β-Cyclodextrin Cavity: Evidence from Oxidation Reactions and Structural Studies

The disposition of cholesterol inside the -cyclodextrin cavity(-CD) was deduced from oxidation of cholesterol secondary alcoholgroups by Ca(OCl)₂ and H₂O₂ in thepyridine–acetic acid system. The amount of cholest-4-ene-3-one formedwas found to be proportional to the concentration of -cyclodextrin,resulting in 56.1% of ketone. The oxidation rate was enhanced by-cyclodextrin and its methyl, polymer and 1 : 1copper(II)–-cyclodextrin derivatives. Detailed investigationsinvolving UV-visible, ¹³C- and ¹H-NMR(T₁, 1D NOE and ROESY) spectroscopic studies were carried out.A binding constant value of 15,385 ± 1500 M^-2 wasobtained for the 2 : 1heptakis-2,6-di-O-methyl--cyclodextrin(DM-CD) : cholesterolcomplex in chloroform from UV studies. Proton and solid state¹³C-CP MAS spectra of the -CD–cholesterol mixtureshowed large magnitude shifts for the protons from the wider end of the-CD cavity as well as those of ring A and ring B of cholesterol. Both1D NOE and ROESY measurements indicated the proximity between ring A andring B protons of cholesterol and the wider end protons of -CD andDM-CD. Besides, analysis of _c,_i and tau;_m from T₁measurements showed not only a lowering of rotational motions but a value of 0.016–0.048 for some of the cholesterol protons, typical of aweak complex. Based on these studies, a probable structure for the 2 : 1complex involving two molecules of -CD/DM-CD was proposed withportions of ring A and ring B being present inside the wider end of the-CD/DM-CD cavity and ring D and the side chain attached atposition 17, projecting into the wider end of the secondCD/DM-CD molecule.     

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.

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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.

     

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.     

“Crowns”, and aromatic sextets in primitive coronoid hydrocarbons

Summary A type of graphs derived from a cycle and associated with primitive coronoids are referred to as crowns. The characteristic polynomials and matching polynomials of crowns are studied. These notions are used to calculate the sextet polynomial for primitive coronoids. Patterns of aromatic sextets are treated in some detail.

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Crowns und aromatische Sextette in einfachen coronoiden Kohlenwasserstoffen

Zusammenfassung Eine Graphentype, die von einem Cyclus abgeleitet ist und mit einfachen Coronoiden verknüpft ist, wird als Crown bezeichnet. Die charakteristischen Polynome und die matching Polynome der Crowns werden untersucht. In diesem Rahmen werden die Sextett-Polynome für einfache Coronoide berechnet. Die Muster der aromatischen Sextette werden im Detail behandelt.

     

Reaction characteristics of cellulose in the LiCl/1,3‐dimethyl‐2‐imidazolidinone solvent system

In order to elucidate the nature of the LiCl/1,3dimethy2imidazolidinone (DMI) solvent system as one of the homogeneous reaction media of cellulose, cellulose acetate (CA) and Omethylcellulose (MC) were prepared using this solvent system, and the distribution of substituents within anhydroglucose units was examined by ¹³CNMR. It was found that (i) homogeneous cellulose solutions can be easily prepared by heating 2, 5–12 and 100 parts of weight of cellulose, LiCl, and DMI, respectively, and (ii) the relative reactivity of hydroxyl groups is in the order C6 > C2 > C3 for both CA and MC. A remarkable feature of this solvent system is that the reaction efficiency in etherification is very high compared with other homogeneous solvent systems.     

Selective reduction of the acyl group in cyclic α-acyl-β-dicarbonyl compounds with sodium cyanoborohydride. Efficient synthesis of cyclic α-alkyl-β-dicarbonyl compounds

Efficient synthesis of cyclic -alkyl--dicarbonyl compounds of the cyclopentane, cyclohexane, tetronic acid, and -pyrone series from the corresponding cyclic -acyl--dicarbonyl compounds under the action of NaBH₃(CN) in a THF--HCl system is described.     

2,2′-Diphenyl-Δ3,3′-bi-3H-indole-1,1′-dioxide: Molecular interactions and crystal structure

The Dinitrone 2,2-diphenyl-^3,3-bi-3H-indole-1,1-dioxide acts as a demethylating and dehydrogenating agent. The mechanism of interaction of the dinitrone with donors and acceptors does not involve intermediate charge-transfer complexes probably due to a self association between dinitrone molecules (as supported by X-ray determinations). The crystal structure of the dinitrone was obtained by direct methods;a=9.967 (2),b=19.817 (3),c=10.875 (2) Å, =111.2 (2)°, space group P2₁/n. The finalR andR _w were 0.089 and 0.063 for all measured reflexes.

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2,2-Diphenyl-^3,3-bi-3H-indol-1,1-dioxid: Molekulare Wechselwirkungen und Kristallstruktur

Zusammenfassung Das Dinitron 2,2-Diphenyl-^3,3-bi-3H-indol-1,1-dioxid wirkt als Demethylierungs- und Oxydationsmittel. Die Wechselwirkung des Dinitrons mit Elektronen-Acceptoren und Elektronen-Donatoren geht wegen der Selbstassoziation zwischen den Dinitron-Molekülen ohne die dazwischenliegende Bildung eines Charge-Transfer-Komplexes vor sich; das wird auch von Röntgenstrukturuntersuchungen gestützt. Die Kristallstruktur wurde mit direkten Methoden ermittelt:a=9.967 (2),b=19.817 (3),c=10.875 (2) Å; =111.2 (2)°. P2₁/n. Die endgültigen WerteR undR _w waren 0.089 und 0.063 für alle gemessenen Reflexe.

     

Triterpene Glycosides from Plants of the Astragalus Genus. III. Structure of Cyclounifolioside C from Astragalus unifoliolatus

The known compound cyclocantogenin (1) and a new cycloartane glycoside cyclounifolioside C (2), which has the structure 24R-cycloartan-3,6,16,24,25-pentaol 3-O--D-glucopyranoside, were isolated from roots of Astragalus unifoliolatus Bunge. The structures of the isolated compounds are established using hydrolysis and spectral data.     

Nitrosation of mefenorex in the presence of cyclodextrins

- and -Cyclodextrin (CD) and heptakis-2,6-di-O-methyl--cyclodextrin (DIMEB) form soluble inclusion compounds with mefenorex (MEF); with -CD a partial inclusion occurs. No solid inclusion compound could be obtained with the four CDs. -, -CD and DIMEB, but not -CD, enhance the nitrosation rate of MEF if the nitrosation assay procedure (NAP test) is applied. During this reaction with - and -CD, solid inclusion compounds of the CDs and nitrosomefenorex (NMEF) precipitate.Part of the Ph.D. thesis of V. Wedelich, Freie Universität Berlin, 1985.     

Sulfur heterocycles. 13. Oxidative chlorination of β-thiolactones. A novel synthesis of β-(chlorosulfinyl)alkanoyl chlorides and 1,2-oxathiolan-5-one 2-oxides

Chlorination of -thiolactones with chlorine or sulfuryl chloride in acetic anhydride at a reactant ratio (RR) of 1:2:1 gives -(chlorosulfinyl)alkanoyl chlorides in 75–89% yields. Oxidative chlorination of -thiolactones with RR of 1:3:2 affords -(chlorosulfinyl)alkanoyl chlorides and cyclic sulfinic anhydrides (1,2-oxathiolan-5-one 2-oxides). The optimum RR for the preparation of 1,2-oxathiolan-5-one 2-oxides is 1:2:2. Hydrolysis of -chloro--(chlorosulfinyl)carbonyl chlorides has given novel -chlorinated sulfinocarboxylic acids.For communication 12, see [1].A. N. Nesmeyanov Institute of Heteroorganic Chemistry, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 2153–2158, September, 1992.     

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.     

Improvement of Solubility and Dissolution of 19-Norprogesterone via Inclusion Complexation

In an effort to modify the solubility and dissolution rate of the contraceptive steroid, 19-norprogesterone in order to improve its bioavailability, the cyclodextrin complexation approach was chosen. In solution, the complex formation with -cyclodextrin (-CD), hydroxyethyl -cyclodextrin (HE--CD) and hydroxypropyl -cyclodextrin (HP--CD) was confirmed by using solubility, UV, IR and ¹H-NMR spectrophotometric techniques. The phase solubility diagrams were categorized as A_L-type. The complexing affinity of the CDs investigated were ranked as follows: -CD > HP--CD > HE--CD. The complexation thermodynamic parameters were obtained from the temperature dependence of the dissociation constants. In the solid state, differential scanning calorimetery (DSC) and optical microscopy methods were utilized to characterize the complexes. Dissolution studies showed that such molecularly encapsulated forms offered a marked improvement in the dissolution rate compared to the parent drug.     

Band structure of even and ions of odd polyenes

The analysis of experimental data for singlet transitions (E _n) of even polyenes (I), cations (II) and anions (III) of odd polyenes show that for infinite chains E (I)/E (II)=E (I)/E (III) = 2:1. It is shown that the energy gap is equal for the three systems. In cases (II) and (III) there is a level (NBMO) in the gap which is vacant in (II) and occupied in (III). That is why the first optical transition in (II) and (III) depends on the semiwidth of the gap.