904296-09-9Relevant academic research and scientific papers
Highly diastereoselective α-hydroxylation of fox chiral auxiliary-based amide enolates with molecular oxygen
Lubin, Hodney,Tessier, Arnaud,Chaume, Gregory,Pytkowicz, Julien,Brigaud, Thierry B.
scheme or table, p. 1496 - 1499 (2010/07/03)
"Figure Presented" Using a trifluoromethylated oxazolidine (Fox) chiral auxiliary, the hydroxylation reaction of enolates was very efficiently performed under smooth and friendly conditions with molecular oxygen as oxidizer. This reaction occurred with an extremely high diastereoselectivlty. After cleavage, the chlral auxiliary Is efficiently recovered and highly valuable enantlopure oxygenated carboxylic acids and alcohols are released.
Fluorine... and π... alkali metal interactions control in the stereoselective amide enolate alkylation with fluorinated oxazolidines (fox) as a chiral auxiliary: An experimental and theoretical study
Sini, Gjergji,Tessier, Arnaud,Pytkowicz, Julien,Brigaud, Thierry
experimental part, p. 3363 - 3370 (2009/04/10)
The α-alkylation of amide enolates by using a pseudo-C2 symmetry trans 4-phenyl-2-trifluoromethyloxazolidine (trans-Fox) as a chiral auxiliary occurs with an extremely high diastereoselectivity (>99% de). The origin of this excellent stereocontrol was investigated by an experimental and theoretical (DFT) study. With this trans chiral auxiliary, both F...metal and π...metal interactions compete to give the same diastereomer through Re face alkylation of the enolate. A 5.5 kcal mol-1 energy difference found between the Re face and the Si face attack transition states is consistent with the complete diastereoselectivity that has been experimentally achieved. On the other hand, in the case of the cis chiral auxiliary (cis-Fox) the competition between the F...metal and π...metal interactions is unfavourable to the diastereoselectivity. In this case, the Re face and the Si face attack transition states were found to be nearly isoenergetic (0.3 kcal mol-1 difference), which is in good agreement with the very low diastereoselectivity observed.
Chiral 4-phenyl-2-trifluoromethyloxazolidine: A high-performance chiral auxiliary for the alkylation of amides
Tessier, Arnaud,Pytkowicz, Julien,Brigaud, Thierry
, p. 3677 - 3681 (2008/03/12)
(Chemical Equation Presented) A bit on the side: Extremely high diastereoselectivities (> 99% de) were attained in the α-alkylation and -allylation of amides by using a trifluoromethylated (sphere) oxazolidine as a chiral auxiliary. Reductive cleavage of the amide bond led to the recovery of this fluorinated chiral auxiliary in high yield.
