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Neier, Reinhard
Résultat de la recherche
Amino-Claisen rearrangements and Diels-Alder reactions of ketene N,O-acetals: Reactivity studies. On the way to a novel tandem process?
2000-1-12, Neuschutz, Klaus, Simone, Jean-Mary, Thyrann, Thomas, Neier, Reinhard
We report the synthesis of N-benzyl-N-[(E)-buta-1,3-dienyl]propanamide (6) and its corresponding O-silyl-subitituted ketene N,O-acetal 7 and their Diels-Alder reaction. Propanamide G reacted smoothly, whereas the yield obtained from 7 was low, probably due to polymerization of the dienophile induced by electron transfer. The ketene N,O-acetals 27a-g were synthesized starting from the corresponding benzamides 25a-e (Scheme 9). The ketene N,O-acetals 27a-g showed increased stabilities and underwent amino-Claisen rearrangements under thermal conditions. Using catalysts, interesting side reactions leading either to the annulated systems, rac-35-37 or to a beta -lactam rac-34 were observed.
Application of the novel tandem process Diels-Alder reaction/Ireland-Claisen rearrangement to the synthesis of rac-juvabione and rac-epijuvabione
2000-1-12, Soldermann, Nicolas, Velker, Joerg, Vallat, Olivier, Stoeckli-Evans, Helen, Neier, Reinhard
The novel tandem process Diels-Alder reaction/Ireland-Claisen rearrangement shows a high diastereoselectivity for the Ireland-Claisen rearrangement starting from the endo-product of the Diels-Alder reaction. Based on this mechanistic knowledge, the novel tandem process could be applied to the synthesis of rac-juvabione.
The novel sequence Diels-Alder reaction/Ireland-Claisen rearrangement applied to acyclic dienophiles: New insights into the selectivity of the Ireland-Claisen rearrangement
1999-1-12, Velker, Joerg, Roblin, Jean Philippe, Neels, Antonia, Tesouro, Ana, Stoeckli-Evans, Helen, Klaerner, Frank-Gerrit, Gehrke, Jan-Stefan, Neier, Reinhard
The new dienes 4a-d, 7 and 11 reacted in good yields with acyclic dienophiles like methyl acrylate and diethyl fumarate in the tandem process Diels-Alder reaction/Ireland-Claisen rearrangement. Analysis of the relative configuration of products 5, 6, 8-10 and 12 indicated that preference for the chair or boat transition state of the Ireland-Claisen rearrangement is strongly influenced by the relative configuration of the substituents of the cyclohexene ring.