Synthesis and polymerization of allyloxyacetaldehyde

Nitrones 9 and 10, formed by treatment of the corresponding aldehydes with N-substituted hydroxylamines, are converted into the cis fused bicyclic compounds 11 and 12, respectively. While this intramolecular cycloaddition as a rule occurs der Z-Konfiguration vorliegen, kann es aber auch zur Reaktion aus der E-Konfiguration kommen'), wobei sich die Anordnung von R2 relativ zu R3/R4 umkehren wurde. Grundsatzlich lassen sich durch 1,3-dipolare Cycloadditionen zwischen Nitronen und 1,Zdisubstituierten Alkenen Isoxazolidine mit drei Chiralitatszentren aufbauen (1). Entsprechendes gilt fur die intramolekulare 1,3-dipolare Cycloaddition zwischen Nitron-und Alkengruppierung (Gl. 2). Hier ist prinzipiell die Bildung der beiden stereoisomeren cis-und trans-verknupften Produkte 2 und des regioisomeren uberbruckten Produkts 3 moglich. Die grundlegenden Arbeiten von LeBel') ergaben entscheidende Unterschiede zwischen den Verbindungen l a und 1 b. Wegen der Kurze der verbindenden Kette in l a ist in diesem Falle die Reaktion uber einen 2-exo-Ubergangszustand so stark begunstigt, dafi sie wie bei der Stammverbindung (R' = Me, R2 = H) auch bei den meisten anderen Verbindungen dieses Typs hoch regio-und stereoselektiv unter Bildung cis-verknupfter 3-Oxa-2-azabicyclo[3. Aufgrund der leichten Spaltbarkeit der NO-Bindung von Isoxazolidinen auf reduktivem Wege kommt insbesondere den intramolekularen Cycloadditionen erhebliche priiparative Bedeutung zu, denn auf diese Weise werden entsprechende monocyclische Verbindungen rnit sterisch definierter Anordnung der Substituenten zuganglich 'I).Wir haben jetzt in 3-Stellung von 1 a bzw.

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Intramolekulare Cycloaddition von Nitronen

Aurich

Boutahar

Köster

et al. 1990

Chem. Ber.

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Equilibrium anionic polymerization of β‐methoxypropionaldehyde

Hashimoto

Sumitomo

Ohsawa

1975

J. Polym. Sci. Polym. Chem. Ed.

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Anionic polymerization of β‐methoxypropionaldehyde (MPA) was carried out in tetrahydrofuran (THF) by using benzophenone–monolithium complex as an initiator. An equilibrium between polymerization and depolymerization was observed at a temperature range of −90 to −70°C. From the temperature dependence of the equilibrium monomer concentration, thermodynamic parameters for the polymerization of MPA in THF were evaluated as follows: ΔHss = −4.8 ± 0.2 kcal/mole, ΔHSS = −22.4 ± 1.3 cal/mole‐deg, and (Tc)ss = −59°C. The thermodynamic change upon the conversion of liquid monomer to condensed polymer was computed from both the partial mixing energy of MPA with THF and the linear relationship between the equilibrium volume fraction of MPA monomer and that of the resulting polymer: ΔH1c = −4.7 ± 0.2 kcal/mole, ΔS1c = −19.5 ± 1.3 cal/mole‐deg, and (Tc)1c = −35°C.

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Equilibrium anionic polymerization of 4,7‐dioxaoctanal and n‐octanal

Hashimoto

Sumitomo

Ohsawa

1978

J. Polym. Sci. Polym. Chem. Ed.

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Equilibrium anionic polymerization of 4,7‐dioxaoctanal (DOA) and n‐octanal (OA) was carried out in tetrahydrofuran in the temperature range of −90 to −68°C, and thermodynamic parameters were evaluated as follows: ΔHss = −4.0 ± 0.1 kcal/mole, ΔSss = −18.4 ± 0.5 cal/mole‐deg, and Tc,ss = −56°C for the DOA system; ΔHsc = −3.4 ± 0.1 kcal/mole, ΔSsc = −15.7 ± 0.4 cal/mole‐deg, and Tc,sc = −59°C for the OA system. Comparison of these values with those in the cases of β‐methoxypropionaldehyde and n‐valeraldehyde made it clear that the aliphatic aldehyde having a longer alkyl group polymerizes with smaller changes of enthalpy and entropy and that the polar‐substituted aldehydes have higher polymerizability than the corresponding unsubstituted aliphatic aldehydes in the temperature range studied. These effects of substituents are interpreted from the viewpoint of the intermolecular interactions of polar groups in monomers and their polymers.

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Synthesis and polymerization of allyloxyacetaldehyde

Cited by 6 publications

References 11 publications

Intramolekulare Cycloaddition von Nitronen

Intramolekulare Cycloaddition von Nitronen

Equilibrium anionic polymerization of β‐methoxypropionaldehyde

Equilibrium anionic polymerization of 4,7‐dioxaoctanal and n‐octanal

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