Ringschlüsse an Chinonylmethanfarbstoffen und analogen Merocyaninen. 4. Mitteilung. Dihydro-anthracenophenazinone

Dihydro-anthracenophenazinones (Cyclization of Quinonylmethane Dyes), 4th Communication. Substituted dihydroanthraceno[1,2-b]phenazinones were synthetized by reaction of 1-alkyl-2,3-dimethyl-quinoxalinium-perchlorates with dichloro- or tetrachloro-1,4-anthraquinone and cyclization of the intermediate quinoxalylidenmethyl-1, 4-anthraquinones. The tetrachloro derivative of 1,4-anthraquinone obtained by chlorination in boiling acetic acid in the presence of iodine is identified to be the 2,3,6,9-isomer. The properties of the dihydroanthraceno[1,2-b]phenazinones are discussed. The visible, mass, and some ¹H-NMR. spectra are given.     

Ringschlüsse an Chinonylmethanfarbstoffen und analogen Merocyaninen. 3. Mitteilung. Chinoide Derivate des anellierten Tetrahydro-isochinolino-chinoxalins. Ringschluss nach 1,7-Verschiebung von Wasserstoff?

Cyclization Reactions of Quinonylmethane Dyes and Analogous Merocyanines. 3. Communication. Quinoid Derivatives of the Anellated Tetrahydro-quinoxalino-quinoxaline. Cyclization Following 1,7-Hydrogene-Shift? The title compounds were obtained by proton catalyzed cyclization of the corresponding 2-(1-alkyl-3-methyl-1,2-dihydroquinoxalin-2-ylidenmethyl)-1,4-naphtho- and 1,4-anthraquinones. The visible and ¹H-NMR.- and some mass spectra of the dyes are given. Mechanistic aspects of the new-type cyclization reaction are discussed.     

Ringschlüsse an Chinonylmethanfarbstoffen und analogen Merocyaninen. 1. Mitteilung. Substituierte Dihydro-naphtho[1,2-b]phenazinone als neuer Typ von “percyclischen” Merocyaninen

Substituted dihydro-naphtho[1,2-b]phenazinone dyes of unexpected properties were synthesized by cyclization of the corresponding (1-alkyl-3-methyl-2-quinoxalinylidenmethyl)-naphtho-quinones. The visible and H-NMR. and some mass spectra of the dyes are discussed.     

Ringschlüsse an Chinonylmethanfarbstoffen und analogen Merocyaninen. 2. Mitteilung. Dihydronaphthophenazinone; Beeinflussung der Löslichkeitseigenschaften durch Substitution,Isolierung und Charakterisierung einer Zwischenstufe des Ringschlusses

Cyclization Reactions of Quinonylmethane Dyes and Analogous Merocyanines. 2. Communication: Dihydro-oxo-naphto-phenazines. Correlation of Solubility and Substitution. Isolation and Characterization of an Intermediate Compound An intermediate compound of the cyclization reaction of 2-chloro-3-(1-cyclohexyl-3-methyl-1,2-dihydroquinoxalin-2-ylidenmethyl)-naphthoquinone was isolated and characterized by spectroscopic methods. 6-Chloro-8-cyclohexyl-5,8-dihydronaphtho[1,2-b]phenazinone was obtained as the final product of this reaction. Several more dihydronaphtho[1,2-b]phenazinone dyes were synthesized. The relationship of substitution and solubility of the dyes is discussed. The visible and ¹H-NMR. and some mass spectra of the dyes are given.     

Ringschlüsse an Chinonylmethanfarbstoffen und analogen Merocyaninen. 6. Mitteilung. Über die Reaktivität des Cyclohexylrestes in 2-Chlor-3-[(1-cyclohexyl-6-fluor-3-methyl-1H-chinoxalin-2-yliden)methyl]-1,4-naphthochinon

Ring Closure in Quinonylmethane Dyes On the Reactivity of the Cyciohexyl Moiety in 2-Chloro-3-[(1-cyclohexyl-6-fluoro-3-methyl-1H-quinoxalin-2-ylidene)niethyl]-1,4-naphthoquinonc The reactive title compound ( 1a , X = F , R ¹ = C⁶H¹¹, R ²=Cl) was obtained from the reaction of 1-cyclohexyl-6-fluoro-2,3-dimethylquinoxalinium perchlorate with 2,3-dichloro-1,4-naphthoquinone. Upon treatment with pyridine and acetic acid in acetone and separation of the desired naphthophenazinone 2a , an unexpected azepinoquinoxaline 4a was isolated. The structure of 4a was determined by its mass and 360-MHz-¹H-NMR. spectra in connection with decoupling experiments.     

Bildung von 4-, 5- und 6gliedrigen Heterocyclen durch ambidoselektive Ringschlüsse von Enolat-Ionen

Formation of 4-, 5- and 6-membered heterocycles by ambidoselective cyclization of enolate anions N-Acylmethyl-N-chloracetyl-2,6-dimethylanilines 4 were cyclized with base to 4-, 5- or 6-membered ring compounds, depending on the substituent R² (Scheme 2). All products can be rationalized as derived from the intermediate enolate anions a and b . The enolate anion a reacts by intramolecular alkylation to yield either 1, 4-oxazines 5 or azetidines 6 (Schemes 1, 3 and 7). The regioselectivity observed is expected on the basis of the allopolarization principle. The enolate anion b reacts only with formation of a new C? C bond (Scheme 5). Comparison with the behaviour of the 2, 6-unsubstituted anilines 9, 1a and 12 , shows a strong dependence not only on electronic but also on steric factors (Scheme 4 and 6).     

Elektrocyclischer Ringschluss als Nebenreaktion bei einer Wolff-Kishner-Reduktion. Über Steroide, 227. Mitteilung

A side reaction occurring in the Wolff-Kishner reduction of certain acetylenic aldehydes (as e.g. 2 or 10 ) is shown to be a synchronous thermal process. The mechanism of this reaction is discussed in terms of the rules of the conservation of orbital symmetry.     

Photochemie von in 4-Stellung substituierten 5-Methyl-3-phenyl-isoxazolen.44. Mitteilung über Photoreaktionen

Photochemistry of 4-substituted 5-Methyl-3-phenyl-isoxazoles. 4-Trideuterioacetyl-5-methyl-3-phenyl-isoxazole ([CD₃CO]- 27 ), upon irradiation with 254 nm light, was converted into a 1:1 mixture of oxazoles [CD₃CO]- 35 and [CD₃]- 35 (Scheme 13). This isomerization is accompagnied by a slower transformation of ([CD₃CO]- 27 ) into [CD₃]- 27 . Irradiation of the isoxazole derivatives 28, 29, 30 and (E)- 31 yielded only oxazoles 36, 37, 38 and (E), (Z)- 39 ; no 4-acetyl-5-alkoxy-2-phenyl-oxazole, 2-acetyl-3-methyl-5-phenyl-pyrrole or 2-acetyl-4-methoxycarbonyl-3-methyl-5-phenyl-pyrrole, respectively, were formed (Scheme 9 and 10). Similarly (E)- 32 gave a mixture of (E), (Z)- 40 only (Scheme 11). Upon shorter irradiation, the intermediate 2H-azirines (E), (Z)- 41 could be isolated (Scheme 11). Photochemical (E)/(Z)-isomerization of the 2-(trifluoro-ethoxycarbonyl)-1-methyl-vinyl side chain in all the compounds 32, 40 and 41 is fast. At 230° the isoxazoles (E)- and (Z)- 32 are converted into oxazoles (E), (Z)- 40 . The same compounds are also obtained by thermal isomerization of the 2H-azirines (E), (Z)- 41 . The most probable mechanism for the photochemical transformations of the isoxazoles, as exemplified in the case of the isoxazole 27 , is shown in Scheme 13. A benzonitrile-methylide intermediate is postulated for the photochemical conversion of the 2H-azirines into oxazoles. 2H-Azirines are also intermediates in the thermal isoxazole-oxazole rearrangement. It is however not yet clear, if the thermal 2H-azirine-oxazole transformation involves the same transient species as the photochemical reaction. A mechanism for the photochemical isomerization of the 2H-azirine 11 to the oxazole 15 is proposed (Scheme 3).     

Arbeiten über Phosphorsäure- und Thiophosphorsäureester mit einem heterocyclischen Substituenten. 4. Mitteilung. 3-Isopropyliden-dithiocarbazinsäure-alkylester und deren Ringschluss zu 5-Alkylthio-1,3,4-thiadiazol-2(3H)-onen

Impurities in crude oily dithiocarbazic acid (2′-methoxy)-ethyl ester causing troubles in the ring closure to 5-(2′-methoxy-ethylthio)-1,3,4-thiadiazol-2(3H)-one and in succeeding reactions are eliminated by using the crystalline 3-isopropylidene-dithiocarbazic acid (2′-methoxy)-ethyl ester, which can be obtained directly by alkylation of potassium dithiocarbazate with 2-methoxy-ethyl bromide in presence of acetone. By the action of phosgene followed by that of water, the isopropylidene compound yields the oily 5-(2′-methoxy-ethylthio)-1,3,4-thiadiazol-2(3H)-one by splitting off the isopropylidene group and by ring closure in one single step.     

Synthese und reaktionen von symmetrisch substituierten s-Triazinen unter hohem druck : Hochdruckreaktionen, 8. Mitteilung

Two extensive mechanisms are proposed for cyclotrimerization of nitriles to s-triazines under high pressure. The availability of these mechanisms is proven by synthesis of some new symmetrically substituted s-triazines; simultaneously, however, their limits are demonstrated. Furthermore, there were found rearrangement and cyclic degradation reactions as reaction possibilities for s-triazines under high pressure. Both reactions are based on an equilibrium in alcohol between symmetrically substituted s-triazine and iminoether.     

Elektronenstruktur und NMR-Parameter von substituierten 5-Phenyl-2,4-pentadiensäuren

The ¹H and ¹³C NMR chemical shifts as well as vicinal HH coupling constants of substituted 5-phenyl-2,4-pentadienoic acids Ar? CH?CH? CR?CR? COOH are reported and discussed in connection with the molecular structure. The ¹³C chemical shift values show an alternation along the chain and can be linearly correlated to the π-electron charge densities as calculated by use of the PPP-method. The effect of para-substituents and solvents upon the ¹³C chemical shifts can be described in terms of the mutual atom-atom polarizabilities.     

Über Pterinchemie. 85. Mitteilung. Polyacetylierte 5,6,7,8-Tetrahydro-D- und -L-neopterine. Ein besonderer Fall von N(5)-Alkylierung des 5,6,7,8-Tetrahydroneopterin-Gerüstes

Polyacetylated 5,6,7,8-Tetrahydro-D - and L -neopterins. A Special Case of N(5)-Alkylation of 5,6,7,8-Tetrahydroneopterins Improved conditions are reported for the preparation of the earlier described (6R)- and (6S)-1′-O,2′-O,3′-O,2-N,5-pentaacetyl-5,6,7,8-tetrahydro-L -neopterins, one of which could be obtained as pure crystals. Its structure, determined by X-ray-diffraction analysis, corresponds to the (6R)-enantiomer. The method has also been used to make the corresponding D -diastereoisomers. Further acetylation of (6RS)-1′-O,2′-O,3′-O,2-N-tetraacetyl-5,6,7,8-tetrahydro-D -neopterin under drastic conditions yields a mixture of several polyacetylated D -neopterin derivatives and a polyacetylated ethyl-tetrahydro-D -neopterin which was isolated in crystalline form and established by X-ray-diffraction analysis to be (6R)-1′-O,2′-O,3′-O,4-O,2-N,2-N,8-heptaacetyl-5-ethyl-5,6,7,8-tetrahydro-D -neopterin.     

C45- und C50-Carotinoide. 5. Mitteilung

C₄₅- and C₅₀-Carotenoids. Synthesis of an Optically Active Cyclic C₂₀-Building Block and of (2R,2′S)-3′,4′-Didehydro-1′,2′-dihydro-2-(4-hydroxy-3-methylbut-2-enyl)-2′-(3-methylbut-2-enyl)-β,ψ-caroten-1′-ol (= C. p. 473) The synthesis of the optically active C₂₀-building block (R)- 16 and of the optically active C₅₀-carotenoid C.p. 473 ( 1 ) starting from (?)-β-pinene is reported.     

Protonenresonanz-spektroskopische Untersuchungen an substituierten Cyclobutenen. Ein Beitrag zur Kenntnis der Bindungsverhältnisse im komplex-gebundenen Cyclobutadien

Complete proton resonance spectra–including all observable ¹³C? H-couplings of a series of substituted cyclobutenes, methylene-cyclobutenes and bismethylene-cyclobutenes have been observed and assigned. The results are discussed with respect to bonding properties in complex-stabilized cyclobutadiene.     

Isomerieerscheinungen an substituierten s-Trithianen und s-Triselenanen. Isolierung von α-Triselenoacetaldehyd

Isomerisations of Triple Substituted s-Trithianes and s-Triselenanes. Isolation of α-Triseleno Acetic Aldehyde α-Trithio acetic aldehyde, α-triseleno acetic aldehyde and 2.4.6-tris-(trimethylsilyl)-s-trithiane are converted to the analogous conformers if they are treated with lewis-acids. α-Triseleno acetic aldehyde has been isolated for the first time by application of a sophisticated method for the preparation of triseleno acetic aldehyde. The conversion of various α-isomers into the β-forms is shown in ¹H-NMR spectra.     

Steroide und Sexualhormone. 248. Mitteilung. Die Partialsynthese von 5α-Dihydrohirundigenin und von 5α-dihydroanhydrohirundigenin

A partial synthesis of dihydroanhydrohirundigenin ( 4 ), a hydrogenation product of naturally occurring anhydrohirundigenin ( 2 ) is described. Furthermore 4 is transformed into the formal dihydroderivative 14 of hirundigenin ( 1 ).     

Langsame Inversion am pyramidal gebundenen Stickstoff: Isolierung und Epimerisierung diastereomerer N-Methoxy-3,3-di-methoxycarbonyl-5-cyan-1, 2-oxazolidine. Vorläufige Mitteilung

Two crystalline diastereomeric N-methoxy-3, 3-di-methoxycarbonyl-5-cyano-1, 2-oxazolidines (II and III) have been isolated. The pyramidal arrangement at the respective nitrogen atoms does not invert at room temperature. The ARRHENIUS activation energy for the epimerization of the thermodynamically less stable isomer to the more stable one in bromoform solution is 29,2 ± 0,5 kcal/Mol (log A = 14,2 ± 0,3).