Conformational analysis of 7,7-dichloro-2,5-dioxabicyclo[4.1.0] heptane by NMR

The ¹H NMR spectra of 7,7-dichloro-2,5-dioxabicyclo-[4.1.0]heptane ( 1 ) were analyzed through the application of programs NMRIT and NMREN2.

1 See Ref. 1.

The half-chair conformation of 1 was obtained from the vicinal coupling constants by the Buys R method.

2 See Ref. 2.

     

Identification de la damascénone et de la β-damascone dans le tabac Burley

The successful identification of damascenone (I)

1 DORICENONE (trade mark of Firmenich & Cie, Geneva).

and β-damascone (III)

2 DORINONE (trade mark of Firmenich & Cia, Geneva)

in Burley tobacco oil was achieved through the use of an efficient vapour phase chromatography/mass spectrometry combination. Thus, the occurrence of β-damascone in nature and the presence of damascenone in an essential oil not related to rose oil were demonstrated.     

Structure et synthèse de la damascénone (triméthyl-2,6,6-trans-crotonoyl-1-cyclohexadiène-1,3), constituant odorant de l'essence de rose bulgare (rosa damascena Mill.

Damascenone

1 DORICENONE (trade mark applied for by Firmenich & Cie, Geneva).

an odoriferous ketone isolated in minute amounts from Bulgarian rose oil (Rosa damascena Mill.) is shown to be trans-2,6,6-trimethyl-1-crotonoyl-cyclohexa-1, 3-diene (I). A synthesis starting from beta;-cyclocitral is described for this conspicuous constituent of rose oil, which displays a powerful fragrance. The synthesis of four related, more saturated ketones, damascones

2 DORINONE (trade mark applied for by Firmenich & Cie, Geneva).

, is also described.     

The He(Iα) Photoelectron Spectra of the Perfluoroderivatives of Trisannelated Benzenes and Tetrakisannelated Cyclooctatetraenes

The He(Iα) photoelectron (PE) spectra of tris(perfluorocyclobuta)benzene 4 (F)

1 3,3,4,4,7,7,8,8,11,11,12,12-Dodecafluorotetracyclo[8.2.0.0^2,5.0^6,9]dodeca-1,5,9-triene

, tris(perfluorocyclopenta)benzene 5 (F)

2 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-Octadecafluoro-2,3,4,5,6,7,8,9-octahydro-1H-trindene.

, tetrakis(perfluorocyclobuta)cyclooctatetraene 6 (F)

3 3,3,4,4,7,7,8,8,11,1l,l2,l2,l5,15,16,16-Hexadecafluoropentacyclo[12.2.0.0^2,5.0^6,9.0^10,13]hexadeca-1,5,9,13-tetraene.

, and of tetrakis(perfluorocyclopenta)cyclooctatetraene 7 (F)

4 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12-Tetracosafluoro-1,2,3,4,5,6,7,8,9,10,11,12-dodeca-hydrotetracyclopenta[a,c,e,g]cyclooctene.

are reported. A tentative assignment of the PE spectra is derived by empirical correlation with those of relevant reference compounds. The results suggest that 6 (F) retains the D_4h-conformation in the gas phase, i.e. A conformation with a planar cyclooctatetraene ring, as observed in the crystal. All four compounds exhibit a sharp increase of their first ionization energies, relative to the corresponding parent hydrocarbons, due to the perfluoro effect.     

Studien Über die Saponine aus der Arznei-Ginseng-Wurzel: Massenspektren von Ginsenoside-Rg1-Decaacetat und Verwandten Verbindungen

Mass spectra of ginsenoside-Rg1 deca-acetate

1 Siehe Lit.2.

and the related dammaran-type triterpene saponin acetates have been studied and a comment is given on the structure of panaxoside A (=ginsenoside-Rg1) proposed by Elyakov, et al .     

Reactions of the Carbonyl Group in Fluorinated Ketones

The chemistry of polyfluorinated ketones has recently received a great deal of attention.

1 A. Ya. Yakoubovich, Usp. Chim. 25, 3 (1956).

2 H. P. Braendlin and E. T. McBee in: Advances in Fluorine Chemistry. Butterworths, London 1963, Vol. 3, p. 1.

3 The review by Braendlin and McBee [2] does not deal only with perfluorinated ketones; moreover, though published in 1963, it is already outdated. The papers discussed in [1,2] will not be reviewed in the present article.

. The carbonyl and imino groups of the fluorinated ketones and their imines react in many different ways. In particular, the electron-attracting perfluoroalkyl groups intensify the electrophilic properties and weaken the nucleophilic properties of the carbonyl group. The perfluoroalkyl group also hinders the heterolytic removal of the hydroxyl group from adducts by reducing the stability of the carbonium ion . The increased electrophilicity of the carbonyl group and the increased stability of the addition products leads not only to a change in reactivity in the characteristic ketone reactions, but also to numerous new reactions which are not observed with non-fluorinated ketones. Thus it is possible to synthesize a wide variety of fluoroorganic compounds from perfluorinated ketones.

4 We have been concerned mainly with hexafluoroacetone, since in addition to being the most readily available and simplest perfluorinated ketone, this is also a typical representative of this class of compounds.

.     

Interfacial tension measurement with the neumann triangle method

The interfacial tensions between polystyrene (PS) and poly(butylene terephthalate)

1 System. name: poly(tetramethylene terephthalate).

(PBT), PS/poly(methyl methacrylate) (PMMA), and PBT/PMMA pairs have been obtained by employing the Neumann Triangle method (NT). The results are in good agreement with those obtained by the breaking thread method. For the first time, the NT method was applied to a reactive polymer pair with an in-situ compatibilizer to measure the interfacial tension. We found that the interfacial tension of the PS/PBT system with a small amount of poly(styrene-co-glycidyl methacrylate)

2 System. name of glycidyl: 2,3-epoxypropyl.

(PS-GMA) is significantly reduced compared to that without PS-GMA.     

On Cardioactive Steroids. VIII. The Synthesis of Bufalin and Resibufogenin Isomers

α-Isobufalin

1 Systematic names are given at the titles of the Exper. Part.

( 1 ) and β-isoresibufogenin ( 3 ) have been synthesized from testosterone by a method which features a novel oxidative furan to pyrone transformation.     

Reversible protection of oligomeric ethylene glycols by bis (2,4-dinitrophenylation) and basic ethanolysis

Bis-(2,4-dinitrophenyl)glycols are stable in the presence of triethylamine but undergo ethanolysis in the presence of hydroxide ions. The quantitative removal of the DNP blocking group allows an integrated scheme to pure glycols from commercially available polyethylene glycol mixtures

1 Mixtures of ethylene glycol oligomers are obtained by anionic polymerization of ethylene oxide. See, for example, G. O. Curme and F. Johnston, Glycols, Reinhold, New York, 1953. They are commercially available (as PEG-200, PEG-400, etc., to indicate the average molecular weight of the major components).

by bis-dinitrophenylation, chromatographic separation, and end-group removal, using high performance liquid chromatography (HPLC) of the bis-(2,4-dinitrophenyl)glycols for purity monitoring. A facile synthetic method for the production of penta-to dodecaglycols in a mixed, aqueous, dioxane solvent system, with fair yields, is also described. The bis-(2,4-dintrophenyl) protection of glycols is a reversible reaction that can be used as (1) a preparative method for pure glycols from readily available commercial polyethylene glycol mixtures; (2) a highly sensitive and accurate analytical method

2 A. Warshawsky, A. Tishbee, and N. Shoef, J. Liq. Chromatogr., submitted for publication.

coupled with HPLC.     

Synthesis of new derivatives of insulin sequence B1-8 with improved solubility

The synthesis of the protected octapeptide N-t-butoxycarbonyl-phenylalanyl-valylasparaginyl-glutaminyl-N^im-tritylhistidyl-leucyl-S-benzhydrylcysteinyl-glycine-hydrazide

1 L

, corresponding to the amino-terminal sequence of the insulin B-chain, is described. Up to the protected octapeptide all intermediates have greatly improved solubility properties in neutral organic solvents in comparison with other synthetic derivatives of the same sequence.     

Heterocyclic Spiro-naphthalenones. Part V. Synthesis of Some 2-Benzazepines from 3,4-Dihydrospiro [furan-2-(5H), 1′(2′H)-naphthalene]-2,5-dione

Compound 2 was rearranged on treatment with 2N NaOH to the 2-benzazepine-3-propanoic

1 See footnote (5) of the preceding paper.

acid 3 . Some aspects of the chemistry of this acid were studied.     

Thermodynamic properties of poly(2,6-dimethyl-1,4-phenylene ether)

The thermodynamic properties of crystalline and amorphous poly(2,6-dimethyl-1,4-phenylene ether) (PPO

1 Registered trademark of General Electric Company.

polymer, General Electric Co.) have been studied calorimetrically between 80 and 570°K. The calculated configurational entropy of this polymer, of similar magnitude to other glass-forming liquids, is consistent with the combination of an unusually high ratio of T_g/T_m, and a low melting entropy.     

Novel Porphyrinoids for Chemistry and Medicine by Biomimetic Syntheses

In 1926 Hans Fischer and Bruno Walach synthesized the first porphyrins.

1 H. Fischer, B. Walach, Justus Liebigs Ann. Chem. 1926 , 450, 164–181.

Currently more than 1400 new articles concerning the synthesis and uses of porphyrins are published every year.

2 CAS Online search for 1994 .

However, the strong interest in these compounds indicated by this is in sharp contrast to their restricted availability. This is reflected in the current price of up to 500 DM for 5 mg of the most important porphyrins used in research and other applications (see Scheme 3). Biomimetic syntheses offer possibilities for an improved approach to porphyrins. By following the example set by nature it is also possible to obtain novel porphyrinoids which are different from naturally occurring porphyrins. This is exemplified by N,N′-bridged porphyrinogens, which have cage structures, inverted porphyrinoids (N atoms in the outer periphery) and, in particular, porphyrins with expanded systems. Among the family of expanded porphyrins are superarenes with up to 34 π electrons. Their pronounced aromaticity is indicated by ¹H NMR spectra, bond length equivalence, planar structures, and electrophilic substitution. With their strong absorption bands, the strongest of which have ? values of > 1000000, a value which exceeds the absorption intensity of all other organic pigments observed until now, and their ability to act as efficient photosensitizers, the expanded porphyrins open interesting perspectives in the fields of photochemistry and photomedicine.     

Quantum semiempirical studies on the formation of aromatic polyamides, 1. Effect of structural parameters of diamines on the polyamidation reaction

A semiempirical quantum-mechanical study of structural and electronic parameters of aromatic diamines was performed using the method AM1. The diamines have been considered as condensation monomers, and the reactivities of both amino groups against acyl chlorides have been computed. The study shows that the amidation reaction is controlled mainly by the global charge on the amino group and, in a much smaller extent, by the frontier orbitals. This behaviour is consistent with the large energy gap between the HOMO 1

1 HOMO: highest occupied molecular orbital.

of the diamine and the LUMO 2

2 LUMO: lowest unoccupied molecular orbital.

of the acyl chloride. It has been found also that the electronic nature of the substituents, affecting the charge of the amino groups, greatly affects the carbons directly joined to these groups. This permits to correlate the reactivities with the calculated charges on these carbons:     

Gas chromatographic—mass spectrometric studies of long chain hydroxy acids.—III.1 The mass spectra of the methyl esters trimethylsilyl ethers of aliphatic hydroxy acids. A facile method of double bond location

Trimethylsilylation has proved to be extremely useful in the gas chromatography and the mass spectrometry of hydroxy acid methyl esters. The characteristic mass spectral fragmentation patterns have shown these derivatives to be superior in some respects to others for structural elucidation; in particular, hydroxylation followed by trimethylsilylation provides a useful method of double bond location in unsaturated fatty acid esters.

1 A preliminary presentation of this method has been given by G. Eglinton at the Lecture etting in Combined Gas Chromatography—Mass Spectrometry at the school of Pharmacy, London, August 9, 1967. It has come to the authors' attention that this method simultaneously developed by Dr. P. Capella, Institute di Industria Agrarie, University of Bologna, Italy^1c (P. Capella and C. M. Zorzut, Anal. Chem. 41 , 1458 (1968).)

     

The mass spectra of some α-aminooxy acids

The mass spectrometric behaviour of six simple α-aminooxy acids is described. Comparison is made with the electron-impact-induced fragmentation of the parent α-amino acids. The differences are in accordance with the observed

1 See Ref. 1.

chemical character of the α-aminooxy acids.     

Stereospecific polymerization of some methyl aryloxymethacrylates

By exposure to ultraviolet and gamma radiation and by the usual methods of thermal polymerization, the stereospecific polymerization of methyl aryloxymethacrylates was carried out at different temperatures in several solvents. Triad tacticity values of the polymers obtained by free-radical and ionic routes were computed from nuclear magnetic resonance spectral data. Results of this investigation support our earlier observation

1 See: K. Saunders, T. Balakrishnan, R. W. Lenz, and K. Hatada, Macromolecules, 12 , 392 (1979).

that, under the conditions used, heterotactic content is the maximum in most of these polymers, thereby justifying the high steric effect of the bulky and polar aryloxy side chain which offers equal isotactic and syndiotactic placements.     

Technische Verfahren zur Synthese von Carotinoiden und verwandten Verbindungen aus 6-Oxo-isophoron. V. Synthese von Astacin

Technical Procedure for the synthesis of Carotenoids and Related Compounds from 6-Oxo-isophorone

1 Teil 4 dieser Reihe: [1].

. V. Synthesis of Astacene Starting from optically inactive astaxanthin intermediates, the highly oxygenated carotenoid astacene was synthesized in seven steps (55% overall yield from 6-oxo-isophorone). Key features of the new approach are base- and acid-catalyzed rearrangements of acetylenic intermediates such as those described in Schemes 2, 7 and 8.     

Isolierung,Struktur und Synthese des Metaboliten von Azapropazon-dihydrat

The renal excretion of AZAPROPAZONE-DIHYDRATE (X)

1 Handelsname: PROLIXAN®. Hersteller: Siegfried AG, Zofingen.

by humans was investigated. Following oral administration a new substance was detected in the urine besides X by TLC. Both compounds were separated by preparative layer chromatography and shown to be unchanged X and its hydroxylated metabolite VIII. The structure of VIII was established by chemical and spectroscopic methods (IR., NMR.) and confirmed by synthesis (Scheme 1).