Janusz Moskal

Conjugated schiff's bases—141: Cycloaddition of heterocumulenes to some 1-oxa-4-azabutadienes

Abstract 1-Oxa-4-azabutadienes proved to be prone to react with some heterocumulenes after 1,3-cycloaddition patterns yielding various 5,5-disubstituted derivatives of 1,3-diaryl-hydanotoins as it was shown by the chemical and spectroscopic analysis. Relatively high yields, mild reaction conditions and a very weak effect of solvent polarity on the reaction rate suggested a synchroneous mechanism involving 1,2-migration of a substituent.

ConjugatedSchiff bases, XIII. sterically congested 1,4-diazabutadienes as dipolar reagents in 1,3-cycloaddition

Use of sterically congested 1,4-diazabutadienes as dipols in reactions with some heterocumulenes has been investigated. A synchronous concerted. mechanism has been considered. The hydantoine-type structure of products has been discussed with respect to their chemical and spectral behaviour.ZusammenfassungEs wird die Verwendung sterisch beanspruchter 1,4-Diazabutadiene als dipolare Agentien bei der Reaktion mit einigen Heterocumulenen untersucht. Ein synchroner, konzertierter Mechanismus wird erwogen. Die Produkte vom Hydantoin-Typ werden mittels ihres chemischen Verhaltens und ihrer spektroskopischen Daten charakterisiert.

Conjugated schiff's bases—10: Control effect of charge resonance coupling on 1,3-cycloaddition of heterocumulenes to some 1,4-diazabutadienes

Abstract 1,3-Dipolar cycloaddition of organic isocyanates to some 1,4-diazabutadienes has been investigated by theoretical and experimental methods. Analysis of HOMO, LUMO interactions indicated the reaction mechanism and the product structure. Cycloaddition proved to be combined with 1,4 sigmatropic-type hydrogen shift and elimination of the initial 1,4-diazabutadiene fragment.

Conjugated schiff's bases.20 cycloaddition of heterocomulenes to some 1,3-heterodienes involving unusual assistance of methyl group☆☆☆

Abstract Highly substituted 1,Δ-diazabutadienes react with aroyl isothiocyanates in a 1,3-dipolar cycloaddition node yielding five-membered thiohydantoin-type heterocycles. The cycloaddition is accompanied by 1,4 shift of hydrogen from a methyl group attached to C2 of the 1,C-diazabutadiene moiety. The mechanism of this reaction is discussed in comparison with similar cycloadditions with aryl isocyanates.

ConjugatedSchiff bases. 15. substituent effect on the cycloaddition of heterocumulenes to some 1-oxa-4-azabutadienes@@@KonjugierteSchiff-Basen, 15. Mitt.: Substituenteneffekte bei der Cycloaddition einiger Heterocumulene mit 1-Oxa-4-azabutadienen

The substituent effect on the cycloaddition of aryl isocyanates to some 1-oxa-4-azabutadienes has been investigated. It has been found that electron-withdrawing groups located in the aryl isocyanate ring distinctly increase the rate of the cycloaddition. The importance of isocyanate nitrogen unshared electrons has been considered. Rate constants and activation parameters have been discussed with respect to the mechanism.ZusammenfassungDer Substituenteneffekt bei der Cycloaddition von Arylisocyanaten an einige 1-Oxa-4-azabutadiene wurde untersucht. Es wurde festgestellt, daß e-anziehende Gruppen am Aryl-isocyanat-Ring deutlich die Geschwindigkeit der Cycloaddition erhöhen. Geschwindigkeitskonstanten und Aktivierungsparameter werden im Hinblick auf den Reaktionsmechanismus diskutiert.

MASS SPECTROMETERY OF THE ISOMERIC OCTAHYDROBENZOPYRIMIDINE-2′-THIONE-4′,1-SPIROCYCLOHEXANE AND 2′-AMINOOCTAHYDROBENZO-3′,1′-THIAZINE-4′,1-SPIROCYCLOHEXANE

Abstract Some authors have shown that tetrahydropyrimidine-2-thiones are hydrated in acidic solution and then isomerise to the 2-imino-or 2-enamino-1,3-thiazine.

Conjugated Schiff's bases. Part 8. Structures and spectral properties of p-NN-dimethylaminoanils of some vicinal diketo-compounds. Positive solvatochromic effect

Solvent effects on the long wavelength u.v. absorption of some conjugated Schiffs bases containing strong electron-releasing substituents in the anil fragment have been investigated. As found from theoretical calculations the absorption in question is due to the n→π* transitions of the unshared electrons of the azomethine nitrogen atom. This absorption exhibits a bathochromic shift when the polarity of the solvent increases. Such abnormal behaviour can be explained by assuming a superdonating character for the azomethine nitrogen atom. The solute forms a molecular arrangement with the solvent which is stabilized in high degree by charge transfer. This seems to be the cause of the bathochromic shift of the n→π* absorption. The charge transfer model considered for the interactions between the solute and aromatic solvents corresponds well to the experimental data. On the other hand the experimental data found for non-aromatic solvents correlate with the Dimroth parameter ET. Considering the complementary influences of Lewis acidity and basicity of the solvent the acidic interactions were estimated by the parameter Z+ defined similarly to the Kossower parameter Z. The estimates of the percentage contribution from solvent acidity and bascity were 96.5 and 3.5%, respectively.

RK. VON ALPHA‐MONOANILEN VON ALPHA,BETA‐DIKETOBUTTERSAEUREANILIDEN MIT ALKOHOLEN UND MERCAPTANEN

Die Acetanilide (I) reagieren mit Nitrobenzolen, wie z.B. (II), in Athanol zu den Aminoathern (III).