Stoeckli-Evans, Helen

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.

1993, Baak, Marcel, Rubin, Yves, Franz, Andreas, Stoeckli-Evans, Helen, Bigler, Laurant, Nachbauer, Jürgen, Neier, Reinhard

Starting from the N-butadienyl-N-alkylpropionamides 1a-1c the corresponding N,0-trimethylsilylacetals could be obtained using the mixture ofLDA and trimethylsilyl chloride in THF. The unexpected reaction sequence Diels-Alder reaction/acylation between the N-butadienyl-N-alkylketene N,0-trimethylsilylacetal ofpropionamide (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,0-trimethylsilylacetals 2a and 2c with acryloyl chloride in a similar sequence gave the bicyclic products rac-8a and mc-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.

2012, Pordea, Anca, Stoeckli-Evans, Helen, Dalvit, Claudio, Neier, Reinhard

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)]

2010, Thevenet, Damien, Neier, Reinhard, Sereda, Olha, Neels, Antonia, Stoeckli-Evans, Helen

The centrosymmetric title compound, C(18)H(28)I(2)O(2), crystallized in the monoclinic space group P2(1)/c with the alkyl chains having extended all-trans conformations, similar to those in the centrosymmetric bromo analogue [Li et al. (2008 (black right triangle)). Acta Cryst. E64, o1930] that crystallized in the triclinic space group P. The difference between the two structures lies in the orientation of the two alkyl chains with respect to the C(aromatic)-O bond. In the title compound, the O-C(alk-yl)-C(alk-yl)-C(alk-yl) torsion angle is 55.8 (5)°, while in the bromo analogue this angle is -179.1 (2)°. In the title compound, the C-atoms of the alkyl chain are almost coplanar [maximum deviation of 0.052 (5) Å] and this mean plane is inclined to the benzene ring by 50.3 (3)°. In the bromo-analogue, these two mean planes are almost coplanar, making a dihedral angle of 4.1 (2)°. Another difference between the crystal structures of the two compounds is that in the title compound there are no halide(midline ellipsis)halide inter-actions. Instead, symmetry-related mol-ecules are linked via C-H(midline ellipsis)? contacts, forming a two-dimensional network.

2012, Bruyneel, Frederic, Letondor, Christophe, Bastuerk, Bjorn, Gualandi, Andrea, Pordea, Anca, Stoeckli-Evans, Helen, Neier, Reinhard

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)]

2006, Loiseau, Francois, Neier, Reinhard, Stoeckli-Evans, Helen

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)]

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.

1996, Marty, Maurus, Stoeckli-Evans, Helen, Neier, Reinhard

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.

2010, Journot, Guillaume, Neier, Reinhard, Stoeckli-Evans, Helen

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)]

2012, Journot, Guillaume, Neier, Reinhard, Stoeckli-Evans, Helen

In 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)]