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Neier, Reinhard
Nom
Neier, Reinhard
Affiliation principale
Fonction
Professeure ordinaire
Email
Reinhard.Neier@unine.ch
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Résultat de la recherche
Voici les éléments 1 - 10 sur 11
- PublicationMétadonnées seulementTandem nucleophilic addition/Diels-Alder reaction of N-butadienyl N,O-ketene silyl acetals with C-60: Stereoselective formation of bicyclic octahydroquinoline-1,2,3,4-tetrahydrobuckminsterfullerenes and combined NMR spectroscopic and computational evaluation of the functionalization reactions(1999)
;Rubin, Yves ;Ganapathi, Padma ;Franz, Andreas ;An, Yi-Zhong ;Qian, WenyuanWe have studied the reactivity of the N,O-ketene N-1,3-butadienyl-N-alkyl-O-silyl acetals 1a-e with C-60 proceeding through a tandem process to give the adducts 2a-e, The addition order of these tandem reactions has been evaluated. The initial nucleophilic Michael-like addition of the electron-rich N,O-ketene acetal moiety proceeds unusually fast at 25 degrees C, followed by an intramolecularly accelerated Diels-Alder step that is highly diastereoselective. The structures of compounds 2a-e were determined from the H-1 and C-13 NMR shifts and from II-II coupling patterns, while their stereochemistry was deduced from 2D T-ROESY NMR experiments. The proposed mechanism for the nucleophilic addition involves single electron transfer followed by radical anion-radical cation recombination. Computational investigations of the reaction pathways, transition states, and conformational energies have been carried out to corroborate the experimental data. - PublicationAccès libreTandem Nucleophilic Addition/Diels-Alder Reaction of N-Butadienyl N,O-Ketene Silyl Acetals with C60: Stereoselective Formation of Bicyclic Octahydroquinolino-1,2,3,4-Tetrahydrobuckminsterfullerenes and Combined NMR Spectroscopic and Computational Evaluation of the Functionalization Reactions(1999)
;Rubin, Yves ;Ganapathi, Padma S. ;Franz, Andreas ;An, Yi-Zhong ;Qian, WenyuanAbstract: We have studied the reactivity of the N,0-ketene N-l,3-butadienyl-N-alkyl-0-silyl acetals 1a-e with C60 proceeding through a tandem process to give the adducts 2a-e. The addition order of these tandem reactions has been evaluated. The initial nucleophilic Michael-like addition of the electron-rich N,O-ketene acetal moiety proceeds unusually fast at 25°C, followed by an intramolecularly accelerated Diels-Alder step that is highly diastereoselective. The structures of compounds 2a-e were determined from the 1H and 13C NMR shifts and from H - H coupling patterns, while their stereochemistry was deduced from 2D T-ROESY NMR experiments. The proposed mechanism for the nucleophilic addition involves single electron transfer followed by radical anion - radical cation recombination. Computational investigations of the reaction pathways, transition states, and conformational energies have been carried out to corroborate the experimental data. - PublicationMétadonnées seulementTandem cycloadditions of N,O-ketene N-1,3-butadienyl-N-alkyo-O-silylacetals with C-60: A straightforward stereoselective synthesis of bicyclic derivatives of 1,2,3,4-tetrahydrobuckminsterfullerene(: Electrochemical Society Inc, 1996)
;Franz, Andreas ;An, Yi-Zhong ;Ganapathi, Padma; ;Rubin, Yves ;Kadish, K. M.Ruoff, R. S.We have studied the reactivity of the N,O-ketene N-1,3-butadienyl-N-alkyl-O-silylacetals 1a-e with C-60 which proceeds through a tandem process to give the adducts 2a-e with high diastereoselectivity. The addition order of these tandem reactions has been evaluated, The structures of compounds 2a-e were determined from the H-1 and C-13 NMR shifts and from the H-H coupling patterns, while the stereochemistry was deduced from 2D T-ROESY NMR experiments. The proposed mechanism for the Michael-type addition step is a single electron transfer, and the source of the C-60-attached proton is discussed. - PublicationMétadonnées seulementPreparation of N-alkylketene-N-butadienyl-N,O-silyl acetals(1996)
;Franz, Andreas ;Eschler, Pierre Yves ;Tharin, Manuel; The synthesis of a series of dienamides 5a-j using Oppolzer's method is described. Using Rathke's method the ketene N,O-silyl acetals 6a-j can be obtained in good yield from the corresponding dienamides. The ketene acetals are obtained free of base and free of salts. They are stable and can be stored at - 20 degrees C. The new dienes are useful reagents for tandem reactions. - PublicationMétadonnées seulementThe preparation and the cascade reactions of N-butadienyl-N-alkylketene N,O-tert-butyldimethylsilyl acetals(: Pergamon-Elsevier Science Ltd, 1996)
;Franz, Andreas ;Eschler, Pierre Yves ;Tharin, ManuelThe preparation of N-butadienyl-N-alkylketene N,O-tert-butyldimethylsilyl acetals (11a-d) from readily available starting materials is described. The cascade Diels-Alder reaction followed by acylation of these ketene acetals yields bicyclic and tricyclic products 7, 13a,b and 14c,d with high diastereoselectivity. Copyright (C) 1996 Elsevier Science Ltd - PublicationMétadonnées seulementTandem reactions combining Diels-Alder reactions with sigmatropic rearrangements(1996)
;Franz, Andreas; Schoepfer, JosephThe developpement of tandem reactions combining Diels-Alder reactions with sigmatropic rearrangements and their application in synthesis will be discussed. [Equation Omitted]. [on SciFinder(R)] - PublicationMétadonnées seulementAn Unexpected Tandem Reaction of N-Butadienyl-N-Alkylketene-N, O-Silylacetals(: The Royal Society of Chemistry, 1996)
;Franz, Andreas ;Eschler, Pierre Yves ;Tharin, Manuel; ;Rzepa, H.J. ;Leach, C.Goodman, J.M. - PublicationAccès libreThe preparation and the cascade reactions of N-butadienyl-N-alkylketeneN,O-tert-butyldimethylsilyl acetals(1996)
;Franz, Andreas ;Eschler, Pierre-YvesThe preparation of N-butadienyl-N-alkylketene N,O-tert-butyldimethylsilyl acetals (11a - d) from readily available starting materials is described. The cascade Diels-Alder reaction followed by acylation of these ketene acetals yields bicyclic and tricyclic products 7.13a,b and 14c,d with high diastereoselectivity. - PublicationAccès librePreparation of N-Alkylketene-N-Butadienyl-N,O-Silyl Acetals(1996)
;Franz, Andreas ;Eschler, Pierre-Yves ;Tharin, Manuel; The synthesis of a series of dienamides 5a-j using Oppolzer’s method is described. Using Rathke’s method the ketene N,O-silyl acetals 6a-j can be obtained in good yield from the corresponding dienamines. The ketene acetals are obtained free of base and free of salts. They are stable and can be stored at -20°C. The new dienes are useful reagents for tandem reactions. - PublicationMétadonnées seulementAn Unexpected Tandem Reaction between N-Butadienyl-N-Alkylketene N,O-Trimethylsilylacetals of Propionamide and Activated Dienophiles like N-Phenylmaleimide or Acryloyl Chloride(1993)
;Baak, Marcel ;Rubin, Yves ;Franz, Andreas ;Stoecklievans, Helen ;Bigler, Laurant ;Nachbauer, JiirgenStarting from the N-butadienyl-N-alkylpropionamides 1a-1c the corresponding N,O-trimethylsilylacetals could be obtained using the mixture of LDA and trimethylsilyl chloride in THF. The unexpected reaction sequence Diels-Alder reaction/acylation between the N-butadienyl-N-alkylketene N,O-trimethylsilylacetal of propionamide (2a-2b) and N-phenylmaleimide produced tricyclic products rac-5a -rac-5b and bicyclic products rac-6a - rac-6b with high diastereoselectivity. The reaction of the N,O-trimethylsilylacetals 2a and 2c with acryloyl chloride in a similar sequence gave the bicyclic products rac-8a and rac-8c. The stepwise synthesis of bicyclic systems of this general structure could only be successfully executed in 26% yield treating the Diels-Alder product rac-10 with LDA.