Potential non-steroidal estrogens and antiestrogens,IV Organic azides in heterocyclic synthesis,part 13: Synthesis of aza- and diazacoumestrols via azido derivatives

Summary 4-Chloro-3-aryl-coumarins and quinolones2 a–e undergo thermolytic ring closure by reaction with sodium azide in refluxing dimethyl formamide to yield indolo[3,2-c]coumarins and indolo[3,2-c]quinolin-6(5H)-ones6 a–e. In the case of the coumarin2 a the azido coumarin5 can be isolated. The mono- and diazacoumestrol-dimethylethers6 a–c are converted into the coumestrol analogues7 a–c and their diacetyl derivatives8 a–c.

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Potentielle nichtsteroidale Östrogene und Antiöstrogene, 4. Mitt.: Organische Azide in der Heterocyclensynthese, Teil 13: Synthese von Aza- und Diazacumöstrolen über Azidzwischenstufen

Zusammenfassung 4-Chlor-3-arylcumarine und-chinolone2 a–e reagieren thermolytisch mit Natriumazid in siedendem Dimethylfomamid unter Ringschluß zu Indolo[3,2-c]cumarinen und Indolo[3,2-c]chinolin-6(5H)-onen6 a–e. Nur aus dem Cumarinderivat2 a kann das zwischenzeitlich gebildete Azidocumarin5 isoliert werden. Die so erhaltenen Mono- und Diazacumöstroldimethylether6 a–c werden in die entsprechenden Cumöstrole7 a–c und ihre Diacetylderivate8 a–c umgewandelt.

     

Observations on the swelling characteristics of the zwitterionic hydrogel of poly(1-3-sulfopropyl)-2-vinyl-pyridinium-betaine hydrogel

Samples of poly[1-(3-sulfopropyl)-2-vinyl-pyridinium-betaine] (PSPV) have been synthesized to high conversion by free radical polymerization in aqueous solution of the zwitterionic monomer SPV with several concentrations of the crosslinker N,N′-methylene-bis-acrylamide (MBA). The densities of the resultant xerogels increased regularly with the content of MBA. Hydrogels obtained by swelling them in water and aqueous KSCN solution were examined by gravimetric and dimensional analysis. The water contents increased with decreasing content of MBA, the value of 92.7 wt% at the lowest MBA content being higher than that for other zwitterionic hydrogels. Enhanced swelling occurred in 1 M aq. KSCN at each MBA content, the total swelling being 98.1 wt% at the lowest crosslinker content. Swelling increased with increasing temperature. An approximate procedure to formulating swelling equilibrium in term of the volume fraction of water in hydrogel, in conjunction with the van’t Hoff equation, yields a small positive value for the enthalpy of swelling. This is compared with values derived similarly for other hydrogels.     

Molecular electrostatic potentials as input for the alignment of HIV-1 integrase inhibitors in 3D QSAR

Comparative molecular similarity indices analysis (CoMSIA), a three-dimensional quantitative structure activity relationship (3D QSAR) paradigm, was used to examine the correlations between the calculated physicochemical properties and the in vitro activities (3'-processing and 3'-strand transfer inhibition) of a series of human immunodeficiency virus type 1 (HIV-1) integrase inhibitors. The training set consisted of 34 molecules from five structurally diverse classes: salicylpyrazolinones, dioxepinones, coumarins, quinones, and benzoic hydrazides. The data set was aligned using extrema of molecular electrostatic potentials (MEPs). The predictive ability of the resultant model was evaluated using a test set comprised of 7 molecules belonging to a different structural class of thiazepinediones. A CoMSIA model using an MEP-based alignment showed considerable internal as well external predictive ability (r2(cv) = 0.821, r2(pred) = 0.608 for 3'-processing; and r2(cv) = 0.759, r2(pred.) = 0.660 for 3'-strand transfer).     

A Study of N-Butyl-(all-trans-retinylidene)amine and Its Protonated Species by 1H- and 13C-NMR. Spectroscopy

The Schiff base of all-trans-retinal was investigated in organic solution by ¹H- and ¹³C-NMR. at high field. Complete assignment of the ¹H-NMR. peaks of N-butyl-(all-trans-retinylidene)amine ( 2 ) and the N-butyl-(all-trans-retinylidene)-ammonium ion ( 3 ) was achieved by INDOR (internuclear double resonance). The vicinal proton coupling constants of the polyene chain show that the π-bond orders remain unchanged in N-butyl-(all-trans-retinylidene)amine relative to all-trans-retinal ( 1 ), but change towards larger π-delocalization in the N-butyl-(all-trans-retinylidene)ammonium ion. At ?-61° only one isomer of N-butyl-(all-trans-retinylidene)ammonium was observed. This was shown to be trans at the imine linkage and independent of the solvent. The trifluoroacetic acid counter-ion can approach the positive charge of the N-atom in the weakly polar solvent dichloromethane but not in the leveling solvent methanol. In dichloromethane the nature of the 1:1 complex is a H-bonded (O^?…H-N⁺) ion-pair whose rate of breaking and forming is rapid at RT. Strong stabilization of the ion-pair resulted from homo-conjugation with a second molecule of trifluoroacetic acid. Excess of acid efficiently diminished the isomerization rate at the C,N-bond.     

Oxidative cleavage of a tricyclic pyridone to a bicyclic lactam-dione

Two equivalents cf anhydrous m-chloroperbenzoic acid (m-CPBA) cleaved the pyridone ring of 10-(3-chlorophenyl)-6,8,9,10-tetrahydrobenzo[b][1,8]naph forming; the ten-membered lactam α-diketone 12-(3-chlorophenyl)-7,8,9,10-tetrahydropyrido[2,3-b]azecine-5,6,11(12H)-trione. Under aqueous conditions, one equivalent of m-CPBA and the same pyridone formed the lactam α-ketol 12-(3-chlorophenyl)-7,8,9,10-tetrahydro-6-hydroxypyrido[2,3-b]azecine-5,11(6H, 12H)-dio     

Mechanisms and Kinetics of Reactions of the O（^1D,^3P） ＋ CF3Cl System

In the stratosphere,CF3Cl(CFC13)can either photodecompose or react directly with atomic oxygen to generate ozone-depleting agents such as Cl and ClO in the gas phase[1—3].Since the1970s,attention has been focused on the effects of these compounds on the …     

Extremely facile ring inversion and rearrangement in fluorobicyclo[2.1.0]pentanes

cis-1,2,3,4,5,5-Hexafluorobicyclo[2.1.0]pentane and 1,2,4,5-tetrafluorobicyclo[2.1.0]pentane have been synthesized from hexafluorobenzene. The former hydrofluorocarbon, which exists entirely in the endo configuration, rearranges to cis-1,2,3,3,4,5-hexafluorocyclopentene below room temperature (E_a = 21.9 kcal/mol, log A = 13.4). The latter undergoes degenerate ring inversion with extraordinary ease (ΔG^‡ = 6.8 ± 0.2 kcal/mol at −55 °C). Density functional calculations indicate that significant bonding between the bridgehead carbons is retained in the ring inversion transition state. Analogous calculations predict for hexafluorobicyclo[1.1.0]butane a considerably lower barrier for ring inversion and more 1,3-bonding in the transition state.     

Isomerization of substituted tricyclic 4,5-dihydropyrazoles

Summary The acid and base catalyzed isomerization of some tricyclic 2-pyrazolines with N-Carbamoyl-,N-thiocarbamoyl-and N-phenyl substituents was investigated. Starting fromcis ortrans 3-H, 3a-H diastereomers, equilibrium mixtures ofcis andtrans diastereomers were prepared which were separated and subsequently studied by¹H NMR and¹³C NMR spectroscopy. A mechanism for the isomerization of the pyrazolines is suggested, supported by a deuterium exchange at C-3a.

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Isomerisierung von einigen substituierten 4,5-Dihydropyrazolen

Zusammenfassung Die Isomerisierung einiger tricyclischer 2-Pyrazoline mit N-Carbamoyl-, N-Thiocarbamoyl-und N-Phenyl-substituenten unter saurer und basischer Katalyse wurde untersucht. Ausgehend von dencis odertrans 3-H,3a-H-Diastereomeren wurdencis- undtrans Gleichgewichtsgemische gewonnen, die getrennt und durch¹H- und¹³C-NMR-Spektroskopie untersucht wurden. Ein Mechanismus für die Isomerisierung von Pyrazolinen wird vorgeschlagen, der durch den Deuteriumaustausch in Position 3a-C unterstützt wird.

     

Cathodic deposition of ternary In+As+Sb alloys and formation of InAsxSb1−x

In+As+Sb alloys have been deposited onto Ni and Ti cathodes from tartaric acid solutions at pH 2. Homogeneous deposits of composition suitable for achieving InAs_xSb_1−x can be obtained from this medium. The As-to-Sb ratio can be controlled by properly selecting solution composition and deposition potential.X-ray photoelectron spectroscopy and X-ray diffraction analyses show that formation of III–V compounds occurs at room temperature. In reacts preferentially with As rather than with Sb, but crystalline phases formed at room temperature are Sb-rich. After annealing the In+As+Sb alloys at 250°C, the composition calculated from cell parameters appears similar to that measured by energy-dispersive X-ray analysis, suggesting that the entire deposit has been converted into the InAs_xSb_1−x crystalline phase.     

Retention,enantioselectivity and enantiomeric elution order of propranolol and its ester derivatives on an alpha1-acid glycoprotein-bonded column

Summary The retention, enantionselectivity and enantiomeric elution order of racemic propranolol (PP) and its ester derivatives (O-acetyl,-propionyl,-butyrul and-valeryl PP) on an ₁-acid glycoprotein (AGP)-bonded column have been investigated by changing eluent composition (eluent pH, buffer concentration, type and content of organic modifier). The retention of these cationic solutes, PP and its ester derivatives, was influenced by eluent pH, ionic strength and organic modifier content. The enantioselectivity was dependent on eluent pH and type of organic modifier. Reversal of the enantiomeric elution order of ester derivatives of PP (O-propionyl-butyryl) and-valeryl PP) occurred around eluent pH 6–7. These results suggst that chiral recognition or binding properties may be altered by the change in eluent composition, espeically eluent pH and type of organic modifier.