Reductivetrans-2,6-diallylation of pyridines with allylboranes. Synthesis oftrans- andcis-2,6-diallyl-1,2,5,6-tetrahydropyridines and their deuterated derivatives

The reductivetrans-2,6-diallylation of pyridines with triallyl- and allyl(dialkyl)boranes has been discovered. Heating (40–100 °C) of pyridine, deuteropyridine, or 3-bromopyridine complexes with triallylborane in the presence of alcohols (ROH or CH₃OD), water, or Et₂NH results in the respectivetrans-2,6-diaIlyl-1,2,5,6-tetrahydropyridines (2,3,22, or25) in 20–97 % yields. A preparative method for the isomerization oftrans-2,6-diallyl compounds2 and25 into the respectivecis-isomers4 and28 by heating them with triallyl- or allyl(dialkyl)boranes (125–150 °C) has been suggested. The hydrogenation oftrans- orcis-2,6-diallyl-1,2,5,6-tetrahydropyridines gavetrans- orcis-2,6-dipropylpiperidines, respectively. Thecis- andtrans-configurations of compounds2 and4 were established by analyzing the NMR spectra ofN-benzyl (7 and13) andN,N-dimethyl (6 and 14) derivatives of piperidine derivatives5 and8. A possible mechanism for the reductive diallylation of pyridines has been discussed.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 693–704, April, 1994.This study was financially supported by the Russian Foundation for Basic Research (Project 93-03-18193).     

Paradigms and Paradoxes: Resonance Stabilization in Diazophenoxides (Quinone Diazides)

Diazophenoxides (quinone diazides) constitute an interesting class of compounds that are seemingly high-energy species on the nonaromatic/aromatic interface. With appropriate substitution and/or annelation, they have found use in the fields of explosives, medicine, and photolithography. Thermochemical information about them is sparse. To aid further understanding of these important chemical species, the current paper discusses a few extant enthalpies of formation from which we tentatively derive a resonance energy of ca. 15 kJ-mol^–1 for the parent, p-species, 4-diazo-2,5-cyclohexadiene-1-one. Interestingly, this value is nearly identical to that recently found for the likewise conjugated diazo compound, ethyl diazoacetate.     

Z-Stereoselective Peterson olefination of ketones

A highly-stereoselective method (90 % of theZ-isomer) was developed for the Peterson olefination of ketones with nerylacetone (1) as an example. The method is based on the introduction of a PhS group, which is removed after completion of the reaction, at the ketone C(3) atom.DeceasedFor the perliminary communication, see Ref. 10.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 509–516, March, 1995.The authors are grateful to the Russian Foundation for Basic Research (grant No. 94.03.08904) and the International Science Foundation (grant NGO000) for financial support of this work.     

Untersuchungen zurFriedel-Crafts-Reaktion. XVI. Darstellung isomerer 2-Acyl- und 3-Acyl-4-methoxyphenole

Acylation of 4-methoxy phenol according toFriedel andCrafts, as well as the rearrangement of its esters according toFries lead always to 2-acyl-4-methoxy phenols or to their demethylated compounds. The unknown 3-acyl-4-methoxy phenols were prepared in two steps: First, the ester is acylated with the corresponding acyl chloride and SnCl₄ in nitromethane. In the second step the resulting ketoesters are hydrolysed. This is a general method. The yields ofmeta-acylphenols are between 40 and 90%. The isomeric 2-acyl-4-methoxy-phenols which were partly unknown or accessible only in low yields have also been prepared for comparative spectral studies (UV, IR, NMR, MS) ofortho- andmeta-acylphenols.

     

Zur Kenntnis der Reaktionsfähigkeit des Thiomorpholins und alkylsubstituierter Thiomorpholine, 4. Mitt.

Thiomorpholine as well as alkyl substituted thiomorpholines and their Sdioxides, respectively, are transformed into the corresponding N-Aminothiomorpholines by nitrosation (1–5) followed by the reduction with zinc in acetic acid/acetic acid anhydride under simultaneous formation of the corresponding N-acetyl derivates, and hydrolysis by hydrochloric acid (6–9). Examples of this method are described. 4-Aminothiomorpholines and their Sdioxides react with aldehydes or ketones to give azomethines (10–31). Acylation with mono-and dicarbonic acid chlorides leads to the N-acyl derivatives32–44.Mannich condensation is also possible. By oxidation with yellow mercury oxide tetracenes are formed (46–47).

Teil der DissertationM. Schmitz, Techn. Hochschule Aachen, 1975.     

2,5,6,7,8-Pentasubstituted (S)- and (R)-[2-chroman-2-yl]ethanols as intermediates for the synthesis of α-tocopherol and its chiral analogs

In the presence of lipase from the yeast Candida cylindracea, partial acetylation of (±)-2-[6-benzyloxy-2,5,7,8-tetramethylchroman-2-yl]ethanol with vinyl acetate gives S-(+)-acetate whose alkaline hydrolysis affords (S)-(–)-alcohol. Repeated enzymatic acetylation of the residual alcohol up to 39% conversion afforded the R-enantiomer. The enantiomeric alcohols were oxidized to (S)- or (R)-aldehydes having the same sign of []_D as the original alcohols. These alcohols were converted into S-(+)- and R-(–)-enantiomers of the antioxidant MDL-73404, a hydrophilic analog of -tocopherol.     

Reactivity of 4-bromomethylquinoline derivatives towards glycine and thioglycolic acid. A new ring system

Condensation of 4-bromomethylquinoline derivatives1 a-1 c with glycine and thioglycolic acid gave the corresponding quinolylmethylglycine and quinolylmethylthioacetic acid derivatives2 a-2 c and2 d-2 f, respectively. Cyclization of2 a-2 f was affected either by polyphosphoric acid or concentrated sulphuric acid to give3 a-3 f. Chlorination of2 a-2 f and3 a-3 f were also accomplished.

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Die Reaktivität von 4-Brommethylchinolin-Derivaten gegenüber Glycin und Thioglycolsäure. Ein neues Ringsystem

Zusammenfassung Die Reaktion von 4-Brommethylchinolin-Derivaten1 a-c mit Glycin und Thioglycolsäure gab die entsprechenden Kondensationsprodukte2 a-c und2d-f.2 a-f konnten mit Polyphosphorsäure bzw. mit konzentrierter Schwefelsäure zu Benzo[c]-2,6-naphthyridinen3 a-f zyklisiert werden.2 a-f und3 a-f waren einer Chlorierung (POCl₃) zugängig.

     

Asymmetric Synthesis of （R）- and （S）-Moprolol

A simple and effective procedure for the enantioselective synthesis of （R）- and （S）-moprolol was described. The key step was the asymmetric synthesis of enantiopure （R）- and （S）-guaifenesin, which were synthesized from enantioenriched （R）-3-chloro-l,2-propanediol and （S）-epichlorohydrin via kinetics of hydrolysis resolution of racemic epichlorohydrin by chiral Salen-Co^Ⅲ complex. The e.e. values of both the optical compounds were above 98%, and the chemical structures of the target compounds were confirmed by ^1H NMR, ^13C NMR, IR, and MS.     

Umsetzungen von Metall- und Metalloidverbindungen mit mehrfunktionellen Molekülen, 16. Mitt.

The reaction of trimethylsilylcarbonamides with halogeno-diorganyl-boranes resp. trihalogenoboranes or organodihalogenoboranes gives monomeric resp. dimeric amidoboranes (borylcarbonamides) and derivatives of 4,8-diaza-1,5-dibora-2,6,9-trioxabicyclo[3.3.1]nonadienes. By reaction of the free acylamides with halogenoboranes in most cases the imide halides could be isolated as the only products. By reaction of the hydrochloride of bis(dimethylamino)-hydroxyborane withn-butyl-lithium followed by addition of the imide halides, the corresponding imidoylamines were formed.¹H,¹¹B, and¹⁹F-nmr spectra, mass spectra and characteristic ir group frequencies are reported.

15. Mitt.:W. Maringgele undA. Meller, Z. anorg. allg. Chem., im Druck.     

Michael reaction. V. Stereochemistry of the NaNH2 catalyzed two-step reaction between phenylacetic acid dialkyl amides and methyl cinnamate or cinnamic acid dialkyl amides

The reaction is investigated between sodium-metallated (NaNH₂) phenylacetic acid dialkyl amides and methyl cinnamate or cinnamic acid dialkyl amides. The thermodynamic equilibrium between the diastereomeric 2,3-diphenylglutaric acid amidoesters or diamides is 5/95 in favour of thethreo-isomer. Under kinetic conditions the stereochemistry of the reaction depends on the nature of the donor and the solvent.

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Michael Reaktion. V. Stereochemie der durch NaNH₂ katalysierten zweistufigen Reaktion zwischen Dialkylamiden der Phenylessigsäure und Methylestern oder Dialkylamiden der Zimtsäure

Zusammenfassung Die Umsetzung zwischen der mit festem NaNH₂ gewonnenen Natriumderivaten der Dialkylamiden der Phenylessigsäure und Methylestern oder Dialkylamiden der Zimtsäure wurde untersucht. Das thermodynamischeE/T-Verhältnis zwischen den gewonnenen diastereomeren Amidestern und Diamiden der 2,3-Diphenylglutarsäure beträgt in allen Fällen 5/95. Das stereochemische Ergebnis unter kinetischen Bedingungen hängt von der Natur des Donators und von den Lösungsmitteln ab.

     

Theoretical study of the influence of para- and meta-substituents on X-pyridineHF hydrogen bonding

The effects of O⁻, N (CH₃)₂, NH (CH₃), NH₂, C₂H₅, CH₃, OH, F, Cl, OF, Br, NO₂ and substituents in para- and meta-positions on X-pyridineHF hydrogen bond has been studied by HF, B3LYP and MP2 methods using 6-311++G(d,p) basis set. The relationship between hydrogen bond formation energy ΔE and electron donating (or withdrawing) of substituents has been investigated. In this respect, population analysis has been performed by atoms in molecules (AIM) and natural bond orbital (NBO) theories. The results of AIM and NBO analyses are in good agreement with calculated energy values. The relationship between Hammett coefficient and complexation energy has been established and the ρ constant has been calculated for hydrogen bonding. There is a relationship between σ and ΔE with a correlation coefficient equal to 0.94.     

Condensation of Stereoisomeric 2-Acetyl-2,3-diphenyloxiranes with Ethyl Trifluoroacetate

The reaction of E-2-acetyl-2,3-diphenyloxirane with ethyl trifluoroacetate in the presence of sodium isopropoxide leads to 3-hydroxy-2,3-diphenyl-6-trifluoromethyl-2,3-dihydro-4H-pyran-4-one. Under the same conditions Z-acetyloxirane forms 3-hydroxy-2-phenyl-5-trifluoromethylfuran as a result of retroaldol cleavage of the initial cyclocondensation product.     

The (E)/(Z)-ratio in the reaction of 5-(2-aryl-2-oxoethyl)-2-thioxo-4-oxo-1,3-thiazolidines with bromine

Summary 3-Aryl-, 3-benzyl-, and 3H-5-(2-aryl-2-oxoethyl)-2-thioxo-4-oxo-1,3-thiazolidines3a–h react with bromine in acetic acid solution to give mixtures of the respective 5-aroylmethylene (E) and (Z) diastereomeric derivatives5 and6. They contain more than 85% of the (E)-diastereomers along with some pure isomers. The intermediacy of the 5-bromo derivatives4 is proven and a plausible route of the reaction is presented. Structures of compounds3–6 are evidenced by analytical and spectral data.

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Das Verhältnis von (E)- und (Z)-Isomeren bei der Reaktion von 5-(2-Aryl-2-oxomethyl)-2-thioxo-4-oxo-1,3-thiazolidinen mit Brom

Zusammenfassung 3-Aryl-, 3-Benzyl- und 3H-5-(2-Aryl-2-oxoethyl)-2-thioxo-4-oxo-1,3-thiazolidine3a–h reagieren mit Brom in essigsaurer Lösung zu Gemischen der entsprechenden diastereomeren 5-Arylmethylen-Derivate ((E) und (Z))5 und6. Sie enthalten mehr als 85% des (E)-Diastereomeren. Die intermediäre Natur der 5-Brom-Derivate4 wird bewiesen; ein Reaktionsweg wird vorgeschlagen. Die Strukturen der Verbindungen3–6 werden durch analytische und spektroskopische Daten abgesichert.

     

Reactions ofo-tosylaminobenzaldehyde withp-aminobenzenesulfonamides. Synthesis and structures of 13-(4-aminosulfonylphenyl)-6,12-epimino-5,11-ditosyl-5,6,11,12-tetrahydrodibenzo[b,f]-1,5-diazocine and itsN-substituted derivatives

The reactions ofo-tosylaminobenzaldehyde (1) withp-aminobenzenesulfonamides (2a-c) yielded 13-(p-RNHSO₂C₆H₄)-6,12-epimino-5,11-ditosyl-5,6,11,12-tetrahydrodibenzo[b f]-1,5-diazocines (3a-c) (R=H (a); 2-thiazolyl (b); or 2,6-dimethoxy-4-pyrimidinyl 2,6-dimethoxy-4-pyrimidinyl (c). The structure of compound3c was confirmed by X-ray diffurction study. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2035–2039, November, 1997.     

Hydrophile Polymergele mit reaktiven Gruppen, 1. Mitt.: Herstellung und Polymerisation von Glucose- und Saccharosemethacrylaten

The synthesis of new hydrophilic polymer carriers on the basis of glucose-and sucrosemethacrylates is described. The monomer mixtures were prepared by reaction of glucose or sucrose with methacrylic anhydride or methacry-loylchloride in pyridine and by transesterification of sucrose with methylmethacrylate. Mixtures of methacrylic esters of glucosides could be obtained by analogous reaction of glucosides with methylmethacrylate. Radical polymerisation of the resulting mixtures of mono-and polyfunctional methacrylic esters of glucose and sucrose yielded crosslinked hydrophilic gels, swellable in water and polar organic solvents. The degree of crosslinking is determined by the ratio of mono- to polyfunctional esters in the monomer mixture, which depends on the molar ratio of reactants in the starting mixture. These neutral reactive carriers are stable to changes inpH and to biological degradation.

     

Viscosity of Aqueous Solutions of Lithium,Sodium, Potassium,Rubidium and Caesium Cyclohexylsulfamates from 293.15 to 323.15 K

The viscosities of aqueous solutions of lithium, sodium, potassium, rubidium and caesium cyclohexylsulfamates were measured at 293.15, 298.15, 303.15, 313.15 and 323.15 K. The relative viscosity data were analyzed and interpreted in terms of the Kaminsky equation, η _r=1+Ac ^1/2+Bc+Dc ². The viscosity A-coefficient was calculated from the Falkenhagen-Dole theory. The viscosity B-coefficients are positive and relatively large. Their temperature coefficient ∂ B/∂ T is negative or near zero for lithium and sodium salts whereas for potassium, rubidium and caesium salts it is positive. The viscosity D-coefficient is positive. This was explained by the size of the ions, structural solute–solute interactions, hydrodynamic effect, and by higher terms of the long-range Debye-Hückel type of forces. From the viscosity B-coefficients the thermodynamic functions of activation of viscous flow were calculated. The limiting partial molar Gibbs energy of activation of viscous flow of the solute was divided into contributions due to solvent molecules and the solute in the transition state. The activation energy of the solvent molecules was calculated using the limiting Gibbs energy of activation for the conductance of the solute ions. The activation energy of the solvent molecules was then discussed in terms of the nature of the alkali-metal ions and their influence on the structure of water. The limiting activation entropy and enthalpy of the solute for activation of viscous flow were interpreted by ion-solvent bond formation or breaking in the transition state of the solvent. The hydration numbers of the investigated electrolytes were calculated from the specific viscosity of the solutions.     

Nucleophilic addition to acetylenes in superbasic catalytic systems. 12. Vinylation of lupinine

The addition of a natural alkaloid lupinine to acetylene in the presence of superbasic catalytic systems (KOH—DMSO, KOBu^t—DMSO, KOH—dioxane) under elevated or atmospheric pressure affords O-vinyllupinine (in up to 88% yield), a promising optically active monomer and intermediate for the preparation of new quinolizidine alkaloids. The same vinyl ether was obtained (in 60% yield) by the reaction of lupinine with vinyl acetate in the presence of Hg(OAc)₂.     

Head to head polymers. XVII: Head to head polypropylene

Head to head polypropylene was prepared by catalytic hydrogenation of eithercis-1,4-poly(2,3-dimethylbutadiene) ortrans-1,4-poly(2,3-dimethylbutadiene) with cobalt 2-ethylhexanoate/triethylaluminium as the hydrogenation catalyst in decahydronaphthalene solution. The hydrogenation occurred predominantly bycis hydrogen addition, but was not stereospecific. The samples of head to head polypropylene were characterized by IR and NMR, particularly by¹³C-NMR spectroscopy. The polymers were amorphous and exhibited glass transition temperatures about 20°C lower than that of head to tail poly-propylene; the glass transition temperatures were measured by DSC and varied somewhat from sample to sample (sufficiently high molecular weight) according to their stereochemistry. TheT _gvalues were confirmed by Rheovibron measurements. The thermal stability of head to head polypropylene is not significantly different from that of either atactic or isotactic head to tail polypropylene.Part XVI:Grossman S., Yamada A., Vogl O., J. Macromol. Sci.-Chem.A 16, 897 (1981).     

Beiträge zur Chemie der Pyrrolpigmente, 26. Mitt.: Zur anaeroben Photochemie von Gallenpigmenten: Die Lumineszenz von Gallenpigment-Partialstruktursystemen und integralen Farbstoffen

The luminescence properties of about twentyfive model compounds representing the three main partial structures of bile pigments (namely pyrromethenes, pyrromethenones and methylenepyrrolylmethylenepyrrolinones) as well as tripyrrines and the geometrical isomers of aetiobiliverdin-IV- are reported. In these compounds there is usually only a very faint or even no fluorescence and phosphorescene as the pathway of deexcitation. Vibrational internal conversion and photoisomerizations at the exocyclic double bonds are the main anaerobic paths of radiationless decay of the excited states.

H. Falk, K. Grubmayr, E. Haslinger, T. Schlederer undK. Thirring, Mh. Chem.109, 1451 (1978).     

Small-angle X-ray scattering studies on the X-ray induced aggregation of malate synthase I. Structural and kinetic studies

Small-angle X-ray scattering measurements on malate synthase in aqueous solution revealed a continuous increase of the intensity in the innermost portion of the scattering curve with increasing measuring time. We have definite evidence that this increase reflects an X-ray induced aggregation of the enzyme particles in the course of the small-angle X-ray scattering experiment. Obviously this aggregation is a consequence of a radiation damage of the particles by the primary beam used in the scattering experiment.The aggregation process of malate synthase was monitoredin situ by smallangle X-ray scattering. For this purpose scattering curves were taken at various stages of aggregation. The analysis of these curves established the increase of the particle dimensions, the retention of the pseudo thickness factor of the native enzyme and the occurrence of one and later on of two pseudo cross-section factors. These results suggest the way how the aggregation might proceed. The results led to a tentative model of the aggregation process in which a one-dimensional side-by-side association of the oblate enzyme particles is followed by a two-dimensional aggregation. An aggregation in the third dimension was not observed during the time covered by our experiment.The time dependence of molecular parameters, for instance of the apparent mean radius of gyration, was used to compare the aggregation of enzyme samples that were irradiated under different experimental conditions. The addition of dithiothreitol to the enzyme solutions as well as the presence of the substrates or of a substrate analogue or of ethanol were found to reduce the rate of aggregation.

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Röntgenkleinwinkeluntersuchungen der durch Röntgenstrahlen induzierten Aggregation der Malatsynthase. I. Strukturuntersuchungen und kinetische Messungen

Zusammenfassung Röntgenkleinwinkeluntersuchungen an wäßrigen Lösungen von Malatsynthase zeigten eine mit der Meßdauer ansteigende Zunahme der Streuintensität im Innenteil der Streukurve. Dieser Intensitätsanstieg spiegelt zweifelsohne eine durch die Röntgenbestrahlung induzierte Aggregation der Enzymteilchen während der Röntgenkleinwinkelmessung wider. Diese Aggregation ist offensichtlich auf einen durch die Primärstrahlung verursachten Strahlenschaden zurückzuführen.Das Fortschreiten der Aggregation der Malatsynthase wurde mit Hilfe der Röntgenkleinwinkelstreuungin situ verfolgt. Zu diesem Zweck wurden Streukurven bei verschiedenen Aggregationsstadien aufgenommen. Die Analyse dieser Kurven zeigte die Zunahme der Teilchendimensionen, das Beibehalten des Pseudodickenfaktors des nativen Enzyms und das Auftreten eines und später zweier Pseudoquerschnittsfaktoren an. Diese Ergebnisse lieferten Hinweise, wie die Aggregation ablaufen könnte, und führten zu einem möglichen Modell für den Aggregationsvorgang. Demnach sollte auf eine eindimensionale, laterale Aggregation der oblaten Enzymteilchen eine zweidimensionale Aggregation folgen. Ein Fortschreiten der Aggregation in der dritten Dimension konnte während der Dauer des Experimentes nicht beobachtet werden.Die zeitliche Abhängigkeit molekularer Parameter, z. B. des apparenten mittleren Streumassenradius, wurde für den Vergleich der Aggregation von Enzymproben, die unter verschiedenen experimentellen Bedingungen bestrahlt wurden, herangezogen. Durch Zugabe von Dithiothreitol oder Ethanol zu den Enzymlösungen oder durch die Anwesenheit der Substrate oder eines Substratanalogen konnte die Aggregationsgeschwindigkeit herabgesetzt werden.