scholarly journals Synthesis of enantiomerically enriched (R)-13C-labelled 2-aminoisobutyric acid (Aib) by conformational memory in the alkylation of a derivative of L-alanine

2011 ◽  
Vol 7 ◽  
pp. 1304-1309 ◽  
Author(s):  
Stephen P Fletcher ◽  
Jordi Solà ◽  
Dean Holt ◽  
Robert A Brown ◽  
Jonathan Clayden
Keyword(s):  
Amino Acids ◽  
Absolute Configuration ◽  
Enantiomeric Purity ◽  
Methyl Groups ◽  
Aminoisobutyric Acid ◽  
The Absolute ◽  
Conformational Memory ◽  
Enantioselective Alkylation ◽  
Derivatives Of

The method of Kouklovsky and coworkers for the enantioselective alkylation of cyclic N-naphthoyl derivatives of amino acids was used to introduce a 13C label into one of the two enantiotopic methyl groups of 2-aminoisobutyric acid (Aib) by retentive alkylation of L-alanine with 13CH3I. Conditions were identified for optimization of yield and enantiomeric purity, and the absolute configuration of the labelled product was established.

Synthesis of N-[(3-Amino-1,2-dicarba-closo-dodecaboran-1-yl)acetyl] Derivatives of α-Amino Acids

2007 ◽  
Vol 72 (12) ◽  
pp. 1697-1706 ◽  
Author(s):  
Galina L. Levit ◽  
Victor P. Krasnov ◽  
Dmitriy A. Gruzdev ◽  
Alexander M. Demin ◽  
Iliya V. Bazhov ◽  
...  
Keyword(s):  
Amino Acids ◽  
Absolute Configuration ◽  
Alkyl Esters ◽  
X Ray ◽  
X Ray Crystallography ◽  
Carbodiimide Method ◽  
The Absolute ◽  
Derivatives Of

The N-[(3-amino-1,2-dicarba-closo-dodecaboran-1-yl)acetyl] derivatives of α-amino acids were prepared starting from N-protected (Ac, Form, Bz, and Boc) 3-amino-1-(carboxymethyl)-o-carboranes and alkyl esters of natural α-amino acids using the carbodiimide method of coupling and removing the ester groups. All the amides obtained were diastereoisomeric mixtures. Some diastereoisomers were separated and the assignment of the absolute configuration of aminocarborane fragments was performed by X-ray crystallography.

Determination of the Complete Absolute Configuration of Petriellin A

2006 ◽  
Vol 59 (6) ◽  
pp. 407 ◽  
Author(s):  
Luigi Aurelio ◽  
Robert T. C. Brownlee ◽  
Jason Dang ◽  
Andrew B. Hughes ◽  
Gideon M. Polya
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Natural Product ◽  
Absolute Configuration ◽  
Structural Determination ◽  
Amino Acid Residues ◽  
The Common ◽  
The Absolute ◽  
Derivatives Of

We report the full structural determination of the depsipeptide petriellin A. The absolute configuration of the amino acid residues, N-methyl isoleucine and N-methyl threonine, have been determined by a combination of HPLC and TLC comparison of synthetic Marfey’s derivatives and Marfey’s derivatives of the natural product hydrolysate. The configuration of the chiral centres in these two N-methylated residues was found to be the same as those of the common unmethylated l-amino acids.

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.

scholarly journals Rapid Organocatalytic Chirality Analysis of Amines, Amino Acids, Alcohols, Amino Alcohols and Diols with Achiral Iso(thio)cyanate Probes

2021 ◽  
Author(s):  
Eryn Nelson ◽  
Jeffrey S. S. K. Formen ◽  
Christian Wolf
Keyword(s):  
Amino Acids ◽  
Absolute Configuration ◽  
Rapid Determination ◽  
Amino Alcohols ◽  
Enantioselective Synthesis ◽  
Widespread Occurrence ◽  
Chiral Compounds ◽  
New Methods ◽  
The Absolute

The widespread occurrence and significance of chiral compounds does not only require new methods for their enantioselective synthesis but also efficient tools that allow rapid determination of the absolute configuration,...

scholarly journals Circular Dichroic Properties of Flavan-3-ols

1999 ◽  
Vol 23 (7) ◽  
pp. 450-451
Author(s):  
Hendrik van Rensburg ◽  
Petrus J. Steynberg ◽  
Johann F. W. Burger ◽  
Pieter S. van Heerden ◽  
Daneel Ferreira
Keyword(s):  
Absolute Configuration ◽  
Heterocyclic Ring ◽  
The Absolute ◽  
Derivatives Of ◽  
Circular Dichroic

CD data of all four diastereoisomers of the permethylaryl ether 3- O-acetyl derivatives of a series of flavan-3-ols permit assignment of the absolute configuration at the stereocentres of the heterocyclic ring.

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