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1.
Ferdinand Krner Markus Schürmann Hans Preut Wolfgang Kreiser 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(1):74-75
Stereoselective hydroboration of (?)‐isopulegol and subsequent fractional crystallization furnishes the title compound, C10H20O2. The relative configuration of the stereogenic centres has been assigned by means of X‐ray diffraction analysis since the monoterpenediol is employed as a versatile chiral building block in stereospecific natural product synthesis. 相似文献
2.
Yoshinobu Inouye 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):e361-e362
The reduction of (1R,8R,11R)‐3,3,11‐trimethyl‐6,6‐ethylenedioxybicyclo[6.3.0]undecan‐2‐one, C16H26O3, (I), gave exclusively an alcohol, C16H28O3, (II). The stereochemistry of the hydroxyl group in (II) was shown as R. The conformation around the eight‐membered carbocycle in (I) differs markedly from that in (II). 相似文献
3.
Zhongtao Wu Prof. Dr. Syuzanna R. Harutyunyan Prof. Dr. Adriaan J. Minnaard 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(44):14250-14255
Based on the asymmetric copper‐catalyzed 1,2‐addition of Grignard reagents to ketones, (R,R,R)‐γ‐tocopherol has been synthesized in 36 % yield over 12 steps (longest linear sequence). The chiral center in the chroman ring was constructed with 73 % ee by the 1,2‐addition of a phytol‐derived Grignard reagent to an α‐bromo enone prepared from 2,3‐dimethylquinone. 相似文献
4.
Dr. Andreas Ole Termath B. Sc. Hanna Sebode M. Sc. Waldemar Schlundt Dr. René T. Stemmler Dr. Thomas Netscher Priv.‐Doz. Dr. Werner Bonrath Prof. Dr. Hans‐Günther Schmalz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(38):12051-12055
By introducing a disposable activating substituent at C‐3, the asymmetric 1,4‐addition to a notoriously unreactive 2‐substituted chromenone was achieved with high levels of (2R)‐stereoselectivity in the presence of a chiral CuI‐phosphoramidite complex as a catalyst. This paved the way for an efficient and conceptually novel synthesis of (R,R,R)‐α‐tocopherol from readily available starting materials. 相似文献
5.
Gowravaram Sabitha Arekuti Maheswara Reddy Singam Siva Sankara Reddy Jhillu Singh Yadav 《Helvetica chimica acta》2013,96(8):1610-1615
Stereoselective syntheses of (?)‐(1R,1′R,5′R,7′R)‐1‐hydroxy‐exo‐brevicomin ( 1 ) and (+)‐exo‐brevicomin ( 2 ) were accomplished from 3,4,6‐tri‐O‐acetyl‐D ‐glucal ( 5 ; Schemes 2 and 3). Chemoselective reduction, Grignard reaction, Barton? McCombie deoxygenation, and ketalization were used as key steps. 相似文献
6.
Henryk Krawczyk Katarzyna Wsek Jacek Kdzia Jakub Wojciechowski Wojciech M. Wolf 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(1):o24-o26
The cyclopropane ring of the title compound, C17H16O2, shows a high level of substituent‐induced bond‐length asymmetry. The carboxyl group adopts a conformation that prompts electron‐density transfer from the ring towards the carbonyl π system. 相似文献
7.
Ferdinand Krner Markus Schürmann Hans Preut Wolfgang Kreiser 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(1):76-77
Esterification of a single diastereomer of 2‐(4‐methylenecyclohex‐2‐enyl)propanol, (II), with (1R,4S)‐(+)‐camphanic acid [(1R,4S)‐4,7,7‐trimethyl‐3‐oxo‐2‐oxabicyclo[2.2.1]heptane‐1‐carboxylic acid] leads to the crystalline title compound, C20H28O4. The relative configuration of the camphanate was determined by X‐ray diffraction analysis. The outcome clarifies the relative and absolute stereochemistry of the naturally occurring bisabolane sesquiterpenes β‐turmerone and β‐sesquiphellandrene, since we have converted (II) into both natural products via a stereospecific route. 相似文献
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Marian Koman Peter Szolcsnyi Tibor Gracza 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):e138-e138
The absolute configuration at the new stereogenic centre during the key step of the total synthesis was established byX‐ray analysis of the title compound, C7H15NO4+·Cl?. 相似文献
10.
Huub Kooijman Anthony L. Spek Henk Kleijn Hendrik L. van Maanen Johann T. B. H. Jastrzebski Gerard van Koten 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):481-483
The configuration of the chiral ring atoms of the title compound, C26H26N2O, obtained in an enantioselective synthesis, has been established relative to the known R configuration of the α‐methylbenzyl moieties. The crystal packing involves a two‐dimensional network of C—H?π interactions between the aromatic rings. 相似文献
11.
F. Sbai M. Dakir A. Auhmani H. El Jamili M. Akssira A. Benharref A. Kenz M. Pierrot 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(8):o518-o520
The stereochemistries of the title compounds, both C16H24Cl2O, have been established by X‐ray diffraction. In both structures, the seven‐membered ring adopts the same conformation, whereas the six‐membered ring shows an envelope conformation in the epoxydodecane structure and a boat conformation in the dodecan‐9‐one structure. 相似文献
12.
Angle Chiaroni Claude Riche Xavier Cachet Brigitte Deguin Michel Koch Franois Tillequin 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(3):358-359
The stereochemistry of the title compound, C20H28O8, a key step in the preparation of analogues of mannostatins, potent inhibitors of α‐mannosidase, has been established. The carboxylic acid group at C1 unexpectedly eclipses the C1—C2 bond. The cyclopropane ring makes a dihedral angle of 109.4 (2)° with the cyclopentene ring. 相似文献
13.
Rafal Kruszynski Wojciech Czestkowski 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(5):402-406
The title compound, C21H26FN3O7, is assembled by N—H...O and O—H...O hydrogen bonds into well‐separated two‐dimensional layers of about 15 Å thickness. The crescent conformation of the molecules is stabilized by weak intramolecular C—H...O and C—H...F hydrogen bonds. The uridine moiety adopts an anti conformation. The ribofuranose ring exists in an envelope conformation. All the endocyclic uracil bonds are shorter than normal single C—N and C—C bonds, and five of them have comparable lengths, which implies a considerable degree of delocalization of the electron density within this ring. 相似文献
14.
Yoshiyuki Kani Shigeru Ohba Seiji Amano Noriko Ogawa Masami Ohtsuka Noritaka Chida 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(5):e222-e222
The relative configuration was determined for the title compound, C26H34O6, which was prepared in a synthetic study on immunosuppressant FR65814. There is an intramolecular hydrogen bond between the hydroxy and epoxy groups. 相似文献
15.
Yoann Coquerel Aurlien Blanc Jean‐Pierre Deprs Andrew E. Greene Marie‐Thrse Averbuch‐Pouchot Christian Philouze Andr Durif 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(12):1480-1481
The title compound, C12H10Cl4O2, has a pseudoasymmetric centre at the methyl‐substituted carbon and, in the solid state, a boat‐like conformation. 相似文献
16.
Dianne D. Ellis Anthony L. Spek 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(4):497-498
In the crystal structure of C15H20O2, molecules are associated by intermolecular hydrogen bonds between the hydroxy function and a keto group [O?O 2.770 (2) Å], forming chains along the [100] direction in the crystal. Both six‐membered rings in the decalin unit adopt envelope conformations; one section of the molecule, encompassing the extended conjugation of a C=C double bond with an enone functionality [C=C—C=O = 175.6 (2)° and C=C—C=C = 176.6 (2)°], is flat, whilst the rest of the molecule is folded relative to the constrained part. The stereochemistry was determined from the R‐(–)‐carvone starting material. 相似文献
17.
Nada Kouti‐Hulita Miroslav
egarac 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(3):o171-o173
In the crystal structure of (R)‐N,N‐diisopropyl‐3‐(2‐hydroxy‐5‐methylphenyl)‐3‐phenylpropylaminium (2R,3R)‐hydrogen tartrate, C22H32NO+·C4H5O6−, the hydrogen tartrate anions are linked by O—H⋯O hydrogen bonds to form helical chains built from (9) rings. These chains are linked by the tolterodine molecules via N—H⋯O and O—H⋯O hydrogen bonds to form separate sheets parallel to the (101) plane. 相似文献
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Péter Király Tibor Soós Szilárd Varga Benedek Vakulya Gábor Tárkányi 《Magnetic resonance in chemistry : MRC》2010,48(1):13-19
The conformational diversity of the (3R,4S,8R,9R)‐9‐[(3,5‐bis(trifluoromethyl)phenyl))‐thiourea](9‐deoxy)‐epi‐cinchonine organocatalyst is discussed. Low‐temperature NMR experiments confirmed a self‐association process, which promotes the quinoline rotation between two intramolecularly hydrogen‐bonded monomeric conformers of the catalyst. The balanced population of the coexisting monomeric and dimeric species allowed us to conduct a structural study of a rather complex conformational dynamics of the pure catalyst. The study is extended by a comparison with other members of the bifunctional amine‐thiourea organocatalyst family. Changes in the molecular structure of the catalysts influence the interplay between intra‐ and intermolecular hydrogen bonding, and yield different extent of catalyst self‐association. By assessing the conformation of the individual states, we established the thermodynamic model of a self‐association promoted conformational transition. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
20.
Ute Baumeister Helmut Hartung Roland Spitzner Michael Felicetti Werner Schroth 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(7):830-831
The (3R*,3′R*) configuration of the title compound, C18H16N2S2, (I), has been unambiguously elucidated by X‐ray analysis. Molecules of (I) have C2 symmetry to a good approximation and a strongly folded shape. The interplanar angle between the two halves of a molecule is 67.11 (6)°. 相似文献