Asymmetric reactions. XLV. Utilisation of the asymmetric transformation to determine the absolute configuration of amines

1973 ◽  
Vol 38 (4) ◽  
pp. 1159-1164 ◽  
Author(s):  
O. Červinka ◽  
V. Dudek
Keyword(s):  
Absolute Configuration ◽  
Asymmetric Reactions ◽  
The Absolute ◽  
Asymmetric Transformation

Stereocontrolled Construction of C-N Rings: The Vanderwal Synthesis of Norfluorocurarine

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Absolute Configuration ◽  
Enantiomeric Excess ◽  
Silver Catalyst ◽  
West Virginia University ◽  
Science And Engineering ◽  
Enantiomerically Pure ◽  
The Absolute ◽  
Asymmetric Transformation ◽  
The University ◽  
Stereogenic Center

Forrest E. Michael of the University of Washington described (Organic Lett. 2009, 11, 1147) the Pd-catalyzed aminative cyclization of 1 to the differentially-protected diamine 3. Peter Somfai of KTH Chemical Science and Engineering observed (Organic Lett. 2009, 11, 919) that [1,2]-rearrangement of 4 proceeded to deliver 5 with near-perfect maintenance of enantiomeric excess. Tushar Kanti Chakraborty of the Central Drug Research Institute, Lucknow applied (Tetrahedron Lett. 2009, 50, 3306) the Ti(III) reduction of epoxides to the Sharpless-derived ether 6, leading to the pyrrolidine 7. Chun-Jiang Wang of Wuhan University devised (Chem. Commun. 2009, 2905) a silver catalyst that directed the absolute sense of the dipolar addition of 9 to 8 to give 10. Homoallyic azides such as 11 are readily prepared in high enantiomeric excess from the corresponding alcohol. Bernhard Breit of Albert-Ludwigs-Universität, Freiburg and André Mann of the Faculté de Pharmacie, Illkirch showed (Organic Lett. 2009, 11, 261) that Rh-mediated hydroformylation could be effected in the presence of the azide. Subsequent reduction delivered the piperidine 12. Jan-E. Bäckvall of Stockholm University applied (J. Org. Chem. 2009, 74, 1988) the protocol for dynamic kinetic asymmetric transformation (DYKAT) that he had developed to the cyanodiol 13. Remarkably, a single enantiomerically- pure diasteromer emerged, which he carried on to 14. Xiaodong Shi of West Virginia University found (Organic Lett. 2009, 11, 2333) that the stereogenic center of 17, even though it ended up outside the ring, directed the absolute configuration of the other centers of 18 as they formed. Jan Vesely of Charles University and Albert Moyano and Ramon Rios of the Universitat de Barcelona established (Tetrahedron Lett. 2009, 50, 1943) that an organocatayst directed the absolute configuration in the addition of 19 to 20 to give 21. Osamu Tamura of Showa Pharmaceutical University effected (Organic Lett. 2009, 11, 1179) cyclization of the malic acid-derived amide 22 to give 23 with high diastereocontrol.

Evaluation of Different Synthetic Routes to (2R,3R)-3-Hydroxymethyl-2-(4-hydroxy- 3-methoxyphenyl)-1,4-Benzodioxane-6-Carbaldehyde

2020 ◽  
Vol 23 (26) ◽  
pp. 2960-2968
Author(s):  
Renáta Kertiné Ferenczi ◽  
Tünde-Zita Illyés ◽  
Sándor Balázs Király ◽  
Gyula Hoffka ◽  
László Szilágyi ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Stereoselective Synthesis ◽  
Cotton Effect ◽  
Enantioselective Synthesis ◽  
Aryl Group ◽  
Target Molecule ◽  
Synthetic Routes ◽  
The Absolute

The reported enantioselective synthesis for the preparation of (+)-(2R,3R)-2-(4- hydroxy-3-methoxyphenyl)-3-hydroxymethyl-1,4-benzodioxane-6-carbaldehyde, precursor for the stereoselective synthesis of bioactive flavanolignans, could not be reproduced. Thus, the target molecule was prepared via the synthesis and separation of diastereomeric O-glucosides. TDDFT-ECD calculations and the 1,4-benzodioxane helicity rule were utilized to determine the absolute configuration. ECD calculations also confirmed that the 1Lb Cotton effect is governed by the helicity of the heteroring, while the higher-energy ECD transitions reflect mainly the orientation of the equatorial C-2 aryl group.

Absolute configuration at C(20) of the derivatives of 21-nor-5α-cholane-20,24-diol

1980 ◽  
Vol 45 (9) ◽  
pp. 2443-2451
Author(s):  
Vladimír Pouzar ◽  
Miroslav Havel
Keyword(s):  
Absolute Configuration ◽  
Side Chain ◽  
Chemical Correlation ◽  
The Absolute ◽  
Derivatives Of

Derivatives of 21-nor-5α-cholane-20,24-diol XI and XIX were prepared by stepwise construction of the side-chain in the position 17β. Their absolute configuration at C(20) was determined on the basis of chemical correlation with the derivatives of 21-nor-5α-cholan-20-ol, XVI and XXIV. The absolute configuration of alcohols XVI and XXIV was determined from the ratio of the yields in which they are formed during the reduction of ketone X and using the benzoate rule. To compounds XI-XVIII the configuration 20R and to compounds XIX-XXVI the configuration 20S has been assigned.

Absolute Stereochemistry of (-)-Wieland-Miescher Ketone as Established by the X-ray Crystallographic and CD Exciton Chirality Methods

1992 ◽  
Vol 57 (7) ◽  
pp. 1459-1465 ◽  
Author(s):  
Nobuyuki Harada ◽  
Tatsuo Sugioka ◽  
Hisashi Uda ◽  
Takeo Kuriki
Keyword(s):  
Structure Analysis ◽  
Absolute Configuration ◽  
X Ray ◽  
The Absolute ◽  
Absolute Stereochemistry

The 8aR absolute stereochemistry of Wieland-Miescher ketone (-)-I was established by the X-ray structure analysis of its bis(4-bromobenzoate) derivatives (1R,6R,8aR)-(+)-IV and (1R,6S,8aR)-(-)-V. The absolute configuration of (-)-I was corroborated further by the application of the CD exciton chirality method to bis(4-bromobenzoates) (+)-IV and (-)-V.

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