Vicarious nucleophilic substitution of hydrogen in nitro-1,6-methano[10]annulenes

Summary The 2- and 3-nitro-1,6-methano[10]annulenes and their 11,11-difluoro derivatives react with carbanions bearing leaving groups at the carbanionic center according to the Vicarious Nucleophilic Substitution of Hydrogen (VNS) scheme. The analogy between corresponding annulenes and naphthalenes with respect to reactivity is discussed.

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Vicarielle nucleophile Substitution von Wasserstoff in Nitro-1,6-methano[10]annulenen

Zusammenfassung 2- und 3-Nitro-1,6-methano[10]annulene und ihre 11,11-Difluoroderivate reagieren mit Carbanionen, die am carbanionischen Zentrum Abgangsgruppen aufweisen, nach dem Schema der vicariellen nucleophilen Substitution (VNS). Die Analogie zwischen entsprechenden Annulenen und Naphthalinen bezüglich ihrer Reaktivität wird diskutiert.

     

Synthesis of Nitrone Analogues of Rar α Selective Retinoid AM580

Synthesis of nitrone analogues of RAR α-selective retinoid Am 580 in which the amide linker is replaced with a nitrone moiety is discribed. The nitrone segment was constructed by oxidizing the corresponding amine using MCPBA or dimethyldioxirane. The resulting nitrone derivatives were found unstable in acidic and basic conditions. The stability limitations of using this nitrone moiety as an amide surrogate are briefed.     

An approach to fused pyrimidine derivativesvia Schiff bases of aromaticortho-nitrocarbaldehydes. An investigation of substituent effects on the reaction course

The synthesis of fused pyrimidines from the Schiff bases of aromatic ortho-nitrocarbaldehydes is reported. The Schiff bases after selective reduction of the nitro group on 10% Pd/C, followed by condensation of the amines formed with orthoesters, are transformed to the corresponding imidates. Heating of the latter in a sealed tube with an excess of ammonia (or with ammonia in ethanol) gives fused pyrimidines. The influence of various substituents in the aromatic ring of the imine moiety of the Schiff bases on the overall yield of fused pyrimidine derivatives has been investigated. Moderate electron-withdrawing groups gave the best results.Institute of Organic Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, PL-01-224 Warszawa, PolandTranslated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 799–805, June, 2000.     

Surune classe de transformations différentielles dans l'espace à trois dimensions. I

Sans résumé     

Zur Theorie der Überkonvergenz

Ohne Zusammenfassung     

Dielectric properties of fine-grained triglycine sulphate (TGS)

The dielectric permittivity ε′ values of triglycine sulphate (TGS) compressed powders with different grain sizes: (1–300) μm have been measured from 300 to 350 K. It has been shown that ε′_max and transition temperature T_c for the average grain size of about 30 μm behave as predicted by the theory of Wang et al. [J. Phys: Condens. Matter 7 (1995) 7163] for cylindric particle geometry.     

Über einige Lösungen der Funktionalgleichung ψ(x)·ψ(x)=ψ(xy)

Ohne Zusammenfassung