Synthetic transformations of methylenelactones of eudesmanic type. Behavior of isoalantolactone under the conitions of heck reaction

By Heck reaction of isoalantolactone with aryl bromides or aryl iodides (3aR,4aS, 8aR,9aR,E)-3-arylmethylidene-8a-methyl-5-methylidenedecahydronaphtho[2,3-b]furan-2(3H)-ones and (4aS,8aR,9aS)-3-arylmethyl-8a-methyl-5-methylidene-4a,5,6,7,8,8a,9,9a-octahydronaphtho[2,3-b]furan-2(4H)-ones, products of the double bond shift, were synthesized. The yields of the arylation products depend on the nature of the catalytic system and on the structure of the aryl halide. The structures of (3aR,4aS,8aR,9aR,E)-3-(3,4-dimethoxybenzylidene)-8amethyl-5-methylidenedecahydronaphtho[2,3-b]furan-2(3H)-one and (4aS,8aR,9aS)-3-(2-methylsulfanylbenzyl)-8amethyl-5-methylidene-4a,5,6,7,8,8a,9,9a-octahydronaphtho[2,3-b]furan-2(4H)-one were proved by XRD analysis.     

Thermochemical studies for determination of the molar enthalpy of formation of aniline derivatives

The standard (p ^o=0.1 MPa) molar enthalpies of combustion atT=298.15 K were measured by static bomb combustion calorimetry for liquidN,N-diethylaniline,N,N-dimethyl-m-toluidine,N,N-dimethyl-p-toluidine, andN-ethyl-m-toluidine. Vaporization enthalpies forN,N-dimethyl-m-toluidine andN-ethyl-m-toluidine were determined by correlation gas chromatography. Derived standard molar values of _f H _m ^o (g) at 298.15 K forN,N-diethylaniline (62.1±7.6);N,N-dimethyl-m-toluidine (72.6±7.3),N,N-dimentyl-p-toluidine (68.9±7.4),N-ethyl-m-toluidine (30.5±3.8 kJ· mol^–1) were obtained.     

Preparation of maleopimar adducts of polyfluoroalkyl esters of tall colophony

Maleopimar adducts of tall colophony esters with alcohols-telomers 1H,1H,5H-perfluoropentane-1-ol, 1H,1H,7H-perfluoroheptane-1-ol, and 1H,1H,9H-perfluorononane-1-ol were synthesized in conditions of Diels-Alder reaction.     

Estimation of the lattice heat capacity of rare-earth compounds

On the basis of the experimental data reported in literature, the contributions of cation mass (m) and molar volume (V) to lattice heat capacity (C) were analyzed. The volumetric-mass formula, C_x=(l —f)·C₁+f·C₂+C_m·(m_x — m_x′), was presented for estimating the heat capacities of rare-earth compounds. In the formula C₁ and C₂ represent the lattice heat capacities of two reference substances respectively, f = V_x—V₁/V₂—V₁ and C_m represents the lattice heat capacity variation with the variation 1 g of cation mass. The equation relating the C_m with temperatures was derived as follows: C_m = 0.084 e ?0.0074T ?0.27 e ?0.045T, and m_x and m_x′ (= (1 - f) m₁₊f m₂) represent the practical and “assumed” cation masses of the substance in question respectively.     

Effect of length and number of interlinking molecules on the strength of adhesion

The fracture energy G of an adhesive bond appears to be a product of two terms: G = G_O [1 + f(R, T)], where G_O is the intrinsic (chemical) strength of the interface and f(R, T), usually much larger than unity, reflects energy dissipated within the adherends at a crack speed R and temperature T. Values of G_O have been determined for interlinked sheets of an SBR elastomer by measuring the peel strength at low rates and high temperatures, and in the swollen state, to minimize internal losses. Both the density ΔN and molecular length L of interlinking molecules were varied. G_O was found to increase in proportion to (ΔN)L^3/2, in accord with the molecular theory of Lake and Thomas. As the peel rate was raised and the test temperature lowered, G was considerably increased by internal dissipative processes, becoming as much as 1000 × G_O near the glass transition. The loss function f(R, T) was found to depend somewhat upon the strand length L, being about twice as large at intermediate peel rates when L was increased by 40%. It also depended on the density ΔN of interlinking molecules, being about twice as large at high peel rates when the density of interlinks was reduced by a factor of six. Thus, the loss function f(R, T) is greater when the interlinking molecules are few and long, and it is lower when they are many and short. However, it is mainly governed by two parameters: peel rate R and temperature difference (T − T_g), in accord with a viscoelastic loss mechanism. © 1996 John Wiley & Sons, Inc.     

The synthesis of derivatives of new tetracyclic heterocyclic systems pyrazolo-bis-azolopyridazines

The synthesis of new tetracyclic systems and new stable tautomers of known systems 11H- 13 and 10H-imidazo[1, 2-b]pyrazolo[4, 3-d]-s-triazolo[3, 4-f]pyridazine 16 , 9H-pyrazolo[3, 4-d]bis-s-triazolo[4, 3-6:5′,1-f]-pyridazine 15 , 10H-pyrazolo[3, 4-d]bis-s-triazolo[4, 3-b:3′,4′-f]pyridazine 17 , and 10H-pyrazolo[4, 3-d)bis-s-triazolo[4, 3-6:5′,1′-f]pvridazine 18 is described.     

Construction of characteristic polynomial of reciprocal graphs from the number of pendant vertices

A method for construction of the characteristic polynomial (CP) coefficients of the three classes of reciprocal graphs, viz., L_n + n(p), C_n + n(p), and K_1,n?1 + n(p), has been developed that requires only the value of n. The working formulas have been expressed in matrix product form, computer programs for which can easily be developed. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Analysis of the melt viscosity and glass transition of polystyrene

The melt viscosity, the glass transition, and the effect of pressure on these are analyzed for polystyrene on the basis of the Tammann-Hesse viscosity equation: log η = log A + B/(T ? T₀). Evidence that the glass transition is an isoviscosity state (log η_g ? 13) for lower molecular weight fractions (M < M_c) is reviewed. For a polystyrene fraction of intermediate molecular weight (M ? 19,000; t_g = 89°C.), it is shown that B is independent of the p–v–T state of the polymer liquid and that dT₀/dP = dT_g/dP. This is consistent with the postulate that B is determined by the internal barriers to rotation in the isolated polymer chain. Relationships are derived for flow “activation energies” at constant pressure and at constant volume, and for the “activation volume.” Values for polystyrene along the zero-pressure isobar and along the constant viscosity, glasstransition line are reported. For the latter, ΔV_g* is constant and corresponds to about 10 styrene units. The “free volume” viscosity equation: log η = log A + b/2.3?, is reexamined. For polystyrene and polyisobutylene, ?_g/b = 0.03, but ?_g and b themselves differ appreciably in these polymers. The parameter b is the product of an equilibrium term Δα and the kinetic term B, and none of these is a “universal” constant for different polymers. The physical significance of the free volume parameter ?, particularly with regard to the “excess” liquid volume, remains undefined. Two new relationships for dT_g/dP, one an exact derivation and the other an empirical correlation, are presented.     

Synthesis of Phenyl- and Benzyl-Substituted Pyrrolidines and of a Piperidine by Intramolecular C-Alkylation. Synthons for tricyclic skeletons

The construction of new or novelly functionalized annulated and bridged tricylic compounds by two consecutive C,C-bond formations (a and b in la , Scheme 1) is described. In a first step, chloroalkyl-substituted aminonitriles yielded pyrrolidines 8 , 15a , 15b , 23 , 25 and piperidine 18 by carbanionic ring closure (Schemes 5, 6, 7 and 8). Subsequent Friedel-Crafts cyclization transformed the β-aminonitriles 8 , 15a , 15b , and 18 either directly or via their carboxylic acid derivatives to the indeno [1, 2-c]pyrrole, 2, 5-methano-3-benzazocine, benz [f]isoindoline and 1, 4-ethano-2-benzazapine skeletons 11 , 16a , 16b and 21 , respectively (Schemes 5, 6 and 7). By classical ring expansion reactions the pyrrolo [3, 4-c]isoquinoline and benzopyrano-[3, 4-c]pyrrole skeletons 28 resp. 31 were obtained from 11 (Scheme 9).     

Phenomenological theory of the kinetics of ultrasonic emulsification

Summary A working model is given for the rate of ultrasonic emulsification, considering the dispersion at the interface (areaA) and the coagulations in the volumeV of the emulsion. A bimolecular coagulation leads to the equationc=c _∞tanhbt;c _∞=(Aα/Vβ)^1/2;b=(Aαβ/V)^1/2 while a monomolecular coagulation givesc=c _∞{1−exp (−at)};c _∞=Aα/Vβ;a=β. The experiments on the dependence of c_∞,a andb uponA andV favour the bimolecular coagulation. The results are satisfactorily explained on general theoretical grounds.

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Zusammenfassung Ein Arbeitsmodell für die Geschwindigkeit der Ultraschallemulgierung wird entwickelt, das Dispersion in der Grenzfl?che (Fl?cheA) und Koagulation im Volumen (V) der Emulsion annimmt. Eine bimolekulare Koagulation führt zu der Gleichung:c=c _∞ tanhbt;c _∞=(Aα/Vβ)^1/2;b=(Aαβ/V)^1/2, eine monomolekulare dagegen zu:c=c _∞{1−exp (at−)};c _∞=Aα/Vβ;α=β. Die Versuche über die Abh?ngigkeit vonc _∞,a undb vonA undV scheinen für bimolekulare Koagulation zu sprechen. Die Ergebnisse werden auf der Basis dieser einfachen theoretischen Grundlagen befriedigend erkl?rt.

     

Kinetics of the gas-phase thermal elimination of N-alkyl-pyrazoles

The kinetic study of the gas-phase thermal elimination reactions of N-ethyl-3,5 dimethyl-pyrazole (I), N-ethyl-pyrazole (II), N-sec-butyl-pyrazole (III), and N-tert-butyl-pyrazole (IV) using a flow system is reported. After obtaining activation parameters for I we carried out competitive reactions with II, III and IV using I as internal standard to obtain their E_a. The values of Δ(ΔH) calculated for II, III and IV agree with the little differences in E_a experimentally found.     

Configurational degeneracy of a set of dipoles in a quasi-two-dimensional system

The purpose of this paper is to provide an exact evaluation of the configurational degeneracy when an arbitrary number (k) of dipoles are placed in a quasi-two-dimensional space (Q2D). This Q2D is made up of three contiguous diagonals 3 × N. Our Q2D space gives to the central sites of the lattice their full coordination number of nearest neighboring compartments. We are going to determine the exact configurational degeneracy W(k, N) when an arbitrary number k of the above mentioned particles are placed in this 3 × NQ2D space. We found that W(k, N) is exactly described by

Development of dissociative force field for all-atomistic molecular dynamics calculation of fracture of polymers

A dissociative force field for all-atomistic molecular dynamics calculations has been developed to investigate impact fracture of polymers accompanying dissociation of chemical bonds of polymer main chain. Energy of dimer molecules was evaluated as a function of both bond-length b and bond-angle θ by CASPT2 calculations, whose quality is enough to describe dissociation of chemical bonds. Because we found that the bond dissociation energy D decreases with increasing bond-angle, we employed the Morse-type function V_Bond(b, θ) = {D − V_Angle(θ)}[1 − exp{−α(b − b₀) − β(b − b₀)²}] where a quartic function V_Angle(θ) = k₁(θ − θ₀) + k₂(θ − θ₀)² + k₃(θ − θ₀)³ + k₄(θ − θ₀)⁴ . This function reproduced well the CASPT2 potential energy surface in a wide range of b and θ. The parameters have been obtained for four popular glassy polymers, polyethylene, poly(methyl methacrylate), poly(styrene), and polycarbonate. © 2019 Wiley Periodicals, Inc.     

Enumeration of the isomers of phenylenes

Summary The [h]phenylene C_6h H_2h+4 isomers are enumerated up toh=12. The numbers are compared with old and new data for C _n H₅ isomers of benzenoids, fluoranthenoids and biphenylenoids.

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Anzahl möglicher Isomerer von Phenylenen

Zusammenfassung Die Anzahl der [h]Phenylen-Isomeren C_6h H_2h+4 wurde bish=12 ausgewertet. Die Zahlen wurden mit alten und neuen Daten für C _n H _s -Isomere von Benzenoiden, Fluoranthenoiden und Biphenyloiden verglichen.

     

Chromatographic Evaluation of the Lipophilic Properties of Selected Pesticides

Monolinuron, chlortoluron, diuron, isoproturon, linuron, diflubenzuron, dimefuron, teflubenzuron, and lufenuron have been chromatographed on an RP-HPLC column and on RP-HPTLC plates with methanol–water in different volume proportions as mobile phases. The retention values log k, and R_M were extrapolated to zero methanol content. Chromatographic lipophilicities (log k_w, R_Mw, _o(HPLC), and _{o (TLC)}) were compared with measured (log P_exp) partition coefficients and with values (A log Ps, IA log P, C log P, log P_Kowin, and x log P) calculated by use of five different software products. The most significant correlations were found between the chromatographic lipophilicities and C log P values. Satisfactory linear correlation was also obtained between lipophilicity (log k_w, R_Mw) and the valence Gutman index (M).     

Hydrogenation of complexes of diastereotopicN-benzoyldehydrodipeptides

The replacement of theN-acetyl group by anN-benzoyl group inN-acyldehydrodipeptides results, first, in an increase in the asymmetric induction in their hydrogenation in the case ofN-Bz-Phe-(S)-Glu.N-Bz-(S)-Phe-(S)-Glu is obtained with a diastereomeric excess (de) of 52 %. Second, no poisoning of the Pd-catalyst by sulfur inN-Bz-Phe-(S)-Met occurs, andN-Bz-(R)-Phe(S)-Met is obtained with ade of 26 %. The formation of complexes ofN-Bz-Phe-AA with Ca²⁺ and Mg²⁺ ions does not, as a rule, affect the diastereoselectivity of the hydrogenation. The structure of the dehydrodipeptides has been determined on the basis of¹H NMR spectra, potentiometric titration, and molecular mechanics calculations.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 884–887, May, 1994.This work was carried out with the financial support of the Russian Foundation for Basic Research (Project 93-03-4646).     

Magic numbers of diamond-like nanostructures

A shell system of diamond- and lonsdalite-like crystal structures has been developed in which nanostructures are represented by nested polyhedral shells, each containing several subshells. The subshells have coordination numbers h, h/2, and h/2m, where h is the group order, and m is the symmetry axis order, which is 48, 24, 6, 8, and 12 for diamond crystals and 24, 12, 2, and 6 for lonsdalite crystals. The shell and subshell sizes and their coordination numbers have been determined, and magic numbers have been calculated for crystal clusters in the structure of diamond (sphalerite XY)—1, 5, 17, 29, 35, 47, 71, 75, 87, 99, 123, 147, 159, 167, 179, 191, 239, 251, 275, 281, 293, 305, 329, 333, 357, 381, 405, 417, 465, 477, 501, …9955—and lonsdalite (wurtzite XY)—1, 5, 17, 18, 27, 33, 39, 48, 50, 68, 77, 89, 92, 98, 104, 122, 125, 137, 144, 147, 159, 165, 171, 177, 183, 195, 207, 231, 232, 238, 253, 259, 283, 295, 304, 307, 319, 325, 337, 361, 370, 394, 406, 415, 417, 420, 432, 438, 444, 450, 474, 483, 489, 501 (the numbers for the Y atoms are italicized). The cluster density increases with size.     

Synthesis of porphyrinyl-nucleosides

Several porphyrinyl-nucleosides were prepared in the reaction of the OH group of one, two or four meso-p-hydroxyphenyl substituents of porphyrin with 5′-O-tosylates of 2′,3′-O-isopropylidene-adenosine or -uridine, or 5′-O-tosylthymidine; the remaining porphyrin meso-substituents were p-tolyl, p-hydroxyphenyl or 4-pyridyl. The following porphyrinyl-nucleosides were obtained with 8–17% yield: meso-di(p-tolyl)di(p-phenylene-5′-O-2′,3′-O-isopropylidene-adenosine) (or -uridine)porphyrins 1,2 , the respective meso-tetranucleosideporphyrins 3,4 -meso-mono(p-phenylene-5′-O-thymidine)porphyrins 5–7 , meso-di(p-tolyl)di(p-phenylene-5′-O-thymidine)porphyrins 8,9 and the meso-di(p-hydroxyphenyl)di(p-phenylene-5′-O-thymidine)porphyrins 10. Other compounds prepared belonged to the series: meso(4-pyridyl)_4?n(p-phenylene-5′-O-2′,3′-O-isopropylideneuridine)_nporphyrin, n = 1, 2 or 4, 11–13. N-Methylation gave the water soluble iodide salts: (N-methyl-4-pyridinium)4_4?n(p-phenylene-5′-O-2′,3′-isopropylideneuridine)_nporphyrins, n = 1, 2 or 4, 14–16. The ms fab showed in most cases stepwise detachment of the CH₂(5′)-nucleoside fragments. The porphyrins meso disubstituted by thymidine represent a convenient substrate for the build-up of both nucleoside units into the oligo/polynucleotide chains.     

N-Glucosides of Aminobenzoic Acids and Aminophenols

N-o-, -m-, and -p-carboxyphenyl-D-glucosylamines and N-o-, -m-, and -p-hydroxyphenyl-D-glucosylamines were synthesized by reaction of D-glucose with o-, m-, and p-aminobenzoic acids and o-, m-, and p-aminophenols. It was demonstrated that both - and -anomers were formed by N-glycosylation of o-, m-, and p-aminobenzoic acids; only -anomers, by N-glycosylation of o-, m-, and p-aminophenols.     

Synthesis,Isolation, and NMR-Spectroscopic Characterization of Fourteen (Z)-Isomers of Lycopene and of Some Acetylenic Didehydro- and Tetradehydrolycopenes

Eight (Z)-isomers of lycopene were prepared by stereocontrolled syntheses and fully characterized by ¹H-NMR, ¹³C-NMR, mass, and UV/VIS spectroscopy: (5Z)-, (7Z)-, (15Z)-, (5Z,5′Z)-, (7Z,7′Z)-, (7Z,9Z)-, (9Z,9′Z)-, and (7Z,9Z,7′Z,9′Z)-lycopene. Six additional (Z)-isomers, namely (9Z)-, (13Z)-, (5Z,9′Z)-, (9Z,13′Z)-, (5Z,9Z,5′Z)-, and (5Z,13Z,5′Z)-lycopene, were isolated in small quantities from isomer mixtures by semiprep. HPLC and were identified by ¹H-NMR spectroscopy.