147666-41-9Relevant academic research and scientific papers
Investigation of a broadly applicable chiral selector used in enantioselective chromatography (Whelk-O 1) as a chiral solvating agent for NMR determination of enantiomeric composition
Koscho, Michael E.,Pirkle, William H.
, p. 3345 - 3351 (2007/10/03)
A chiral solvating agent (CSA) based on the chiral selector used in the Whelk-O 1 chiral stationary phase (CSP) was prepared and its scope evaluated. This chiral selector possesses a cleft flanked with aromatic groups and produces upfield chemical shifts for analytes, which are held in this cleft. The enantiomers of each of the Whelk-O 1 resolvable analytes surveyed show non-equivalent 1H NMR spectra at room temperature with the addition of only 0.5 equiv of the CSA. Similar non-equivalence is sometimes noted for enantiomers, which do not resolve on this CSP. In such cases, it is apparent that a hydrogen bond acceptor is required and higher CSA to substrate ratios and/or lower temperatures may be needed if adequate resolution of enantiomeric signals is to be obtained.
Synthetic applications of the β-lithiation of β-Aryl secondary amides: Diastereoselective and enantioselective substitutions
Lutz, Gary P.,Du, Hua,Gallagher, Donald J.,Beak, Peter
, p. 4542 - 4554 (2007/10/03)
The sequence of β-lithiation and electrophilic substitution of β-aryl secondary amides is reported. The lithiations occur regioselectively at the β-position, and the resulting lithiated intermediates can be reacted with a wide range of electrophiles to give substituted products. Reactions of β-lithiated amides bearing an α-substituent provide substituted products with high diastereoselectivity. Electrophilic substitutions of β-lithiated N-methylamides in the presence of the chiral diamine (-)-sparteine provide highly enantioenriched products. The methodology is used to synthesize enantioenriched β-aryl β-substituted amides, acids, and lactones.
Enantioselective Conjugate Reduction of α,β-Unsaturated Carboxamides with Semicorrin Cobalt Catalysts
Matt, Peter von,Pfaltz, Andreas
, p. 691 - 700 (2007/10/02)
Chiral semicorrin cobalt complexes, prepared in situ from cobalt(II) chloride and the free ligands, are efficient, highly enantioselective catalysts for the conjugate reduction of α,β-unsaturated carboxamides with sodium borohydride.Enantiomeric excesses of up to 99percent, essentially quantitative yields, and high substrate/catalyst ratios (1000-10 000:1) are attractive attributes of this catalytic process.
