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Stoeckli-Evans, Helen
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Stoeckli-Evans, Helen
Affiliation principale
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helen.stoeckli-evans@unine.ch
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Voici les éléments 1 - 10 sur 52
- PublicationMétadonnées seulementApplication of the novel tandem process Diels-Alder reaction/Ireland-Claisen rearrangement to the synthesis of rac-juvabione and rac-epijuvabione(2000-1-12)
; 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. - PublicationMétadonnées seulementCatalytic Epoxidation of Alkenes by the Manganese Complex of a Reduced Porphyrinogen Macrocycle(2012)
; ; The present paper details the first application of a fully reduced meso-octamethylporphyrinogen macrocycle as an effective ligand for simple operative manganese-catalyzed alkene epoxidn. The efficiency of the novel catalyst was detd. in the presence of various oxidants, apical ligands and acidic/basic additives. Higher reactivity was found in favor of electron-rich alkenes, whereas an electron-deficient conjugated alkene appeared to be a poor substrate in the screening. Sulfur additives were active as apical ligands, whereas nitrogen-contg. additives influenced the reactivity only moderately. Cis-Stilbene and 3?-acetoxy-5-cholestene were epoxidized in a stereoselective manner. The x-ray structures of the new manganese complexes were detd. and showed a rigid planar coordination geometry of the satd. macrocyclic ligand to the metal center. [on SciFinder(R)] - PublicationMétadonnées seulementDiastereoselective synthesis of (1S,2S,3R,6S) 3-chloro-3-methyl-6-isopropenyl-1,2-cyclohexanediol via Prins reaction induced by zinc and trimethylsilyl chloride(1996)
; While attempting to synthesize a potential inhibitor of the biosynthetic step of formation of PEG, a novel catalytic system inducing the Prins reaction was discovered. Treatment of epoxy geranial with Zn and trimethylsilyl chloride gave (1S,2S,3R,6S) 3-Chloro-3-methyl-6-isopropenyl-1,2-cyclohexanediol in high diastereoselcctivity. - PublicationAccès libreAn Unexpected Tandem Reaction between N-Butadienyl-N-alkylketeneN,0-Trimethylsilylacetals of Propionamide and Activated Dienophiles like N-Phenylmaleimide or Acryloyl Chloride(1993)
; - PublicationMétadonnées seulementrac-(R)-2-[(2R,5R)-5-Methyltetrahydrofuran-2-yl]propanoic acid(2006)
; In the crystal structure of rac-(R)-2-[(2R,5R)-5-methyltetrahydrofuran-2-yl]propanoic acid, C8H14O3, the 2,5-THF ring junction is cis. The relative configuration of position 2 in the propanoic acid group is the same as that in positions 2 and 5 in the THF ring. In the crystal structure, symmetry-related mols. are linked by O-H...O H bonds to form centrosym. dimers. Crystallog. data are given. [on SciFinder(R)] - PublicationMétadonnées seulement2,2'-(Propane-2,2-diyl)bis(1H-pyrrole)2,2'-(Propane-2,2-diyl)bis(1H-pyrrole), C11H14N2, crystd. with 2 independent mols. (A and B) in the asym. unit. The 2 mols. differ only slightly, with the pyrrole rings being inclined to 1 another at a dihedral angle of 87.67(8)° in mol. A and 88.09(7)° in mol. B. In the crystal, there are no classical H bonds, but the 2 pyrrole NH groups of 1 mol. are involved in N-H···? interactions with the pyrrole rings of the other mol. In this manner, a compact box-like arrangement of the 2 independent mols. is formed. Crystallog. data are given. [on SciFinder(R)]
- PublicationMétadonnées seulement5-Hydroxyalkyl derivatives of tert-butyl 2-oxo-2,5-dihydro-1H-pyrrole-1-carboxylate: diastereoselectivity of the Mukaiyama crossed-aldol-type reaction(2009)
; ; The title compds., rac-(1'R,2R)-tert-Bu 2-(1'-hydroxyethyl)-3-(2-nitrophenyl)-5-oxo-2,5-dihydro-1H-pyrrole-1-carboxylate, C17H20N2O6, (I), rac-(1'S,2R)-tert-Bu 2-[1'-hydroxy-3'-(methoxycarbonyl)propyl]-3-(2-nitrophenyl)-5-oxo-2,5-dihydro-1H-pyrrole-1-carboxylate, C20H24N2O8, (II), and rac-(1'S,2R)-tert-Bu 2-(4'-bromo-1'-hydroxybutyl)-5-oxo-2,5-dihydro-1H-pyrrole-1-carboxylate, C13H20BrNO4, (III), are 5-hydroxyalkyl derivs. of tert-Bu 2-oxo-2,5-dihydropyrrole-1-carboxylate. Crystallog. data are given. In all three compds., the tert-butoxycarbonyl (Boc) unit is orientated in the same manner with respect to the mean plane through the 2-oxo-2,5-dihydro-1H-pyrrole ring. The hydroxyl substituent at one of the newly created chiral centers, which have relative R,R stereochem., is trans with respect to the oxo group of the pyrrole ring in (I), synthesized using acetaldehyde. When a larger aldehyde was used, as in (II) and (III), the hydroxyl substituent is cis with respect to the oxo group of the pyrrole ring. Here, the relative stereochem. of the newly created chiral centers is R,S. In (I), O-H...O H bonding leads to an interesting hexagonal arrangement of symmetry-related mols. In (II) and (III), the hydroxyl groups are involved in bifurcated O-H...O H bonds, and centrosym. H-bonded dimers are formed. The Mukaiyama crossed-aldol-type reaction was successful when using the 2-nitrophenyl-substituted hydroxypyrrole, or the unsubstituted hydroxypyrrole, and B trifluoride Et2O as catalyst. The synthetic procedure leads to a syn configuration of the two newly created chiral centers in all three compds. [on SciFinder(R)] - PublicationMétadonnées seulementSynthesis and Reactions of 2-[1-Methyl-1-(pyrrolidin-2-yl)ethyl]-1H-pyrrole and Some Derivatives with Aldehydes: Chiral Structures Combining a Secondary-Amine Group with an 1H-Pyrrole Moiety as Excellent H-Bond Donor(2012)
; ; ; The synthesis of compd. I (R = H) and its derivs. I (R = CF3, CO2Me) combining a pyrrolidine ring with an 1H-pyrrole unit is described. Their attempted usability as organocatalysts was not successful. Reacting these simple pyrrolidine derivs. with (E)-cinnamaldehyde led to tricyclic products. The final, major products were the pyrroloindolizidine tricycles, e.g. II, obtained via the iminium ion reacting intramolecularly with the nucleophilic ?-position of the 1H-pyrrole moiety. [on SciFinder(R)] - PublicationMétadonnées seulementThe 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)
; - PublicationMétadonnées seulement2-[2-(Pyrrolidin-2-yl)propan-2-yl]-1H-pyrrole and its amide derivative 1-{2-[2-(1H-pyrrol-2-yl)propan-2-yl]pyrrolidin-1-yl}ethanoneIn the title compds., C11H18N2, (II), and C13H20N2O, (III), the pyrrolidine rings have twist conformations. Compd. (II) crystallizes with two independent mols. (A and B) in the asym. unit. The mean planes of the pyrrole and pyrrolidine rings are inclined to one another by 89.99 (11) and 89.35 (10)° in mols. A and B, resp. In (III), the amide deriv. of (II), the same dihedral angle is much smaller, at only 13.42 (10)°. In the crystal structure of (II), the individual mols. are linked via N-H···N hydrogen bonds to form inversion dimers, each with an R22(12) graph-set motif. In the crystal structure of (III), the mols. are linked via N-H···O hydrogen bonds to form inversion dimers with an R22(16) graph-set motif. [on SciFinder(R)]