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A highly enantioselective (91‐ > 99% ee) Michael addition of α‐nitroacetate to α,β‐unsaturated pyrazolamide was developed in the presence of a bifunctional squaramide. Satisfactory isolated yields (42%‐99%) have been achieved with a wide range of α,β‐unsaturated pyrazolamides, albeit acceptor of this type displayed poor reactivity in the precedent reports. The adducts resulting from this protocol...
Chiral salalen ligands derived from (S)‐proline and derivatives of salicyaldehydes were synthesized, and their in‐situ generated Cu (II) complexes were evaluated in the asymmetric Henry reaction. Salalen ligand of different substituents on the phenyl moiety showed remarkable effect on the enantioselectivity of nitro‐aldol product of 4‐nitrobenzaldehyde and nitromethane. Cu (II) complex generated in...
New chiral high‐performance liquid chromatography (HPLC) method for the enantiomeric resolution of quinolones is developed and described. The column used was Chirobiotic T (150 × 4.6 mm, 5.0 μm). Three mobile phases used were MeOH:ACN:Water:TEA (70:10:20:0.1%), (60:30:10:0.1%), and (50:30:20:0.1%). The flow rate of the mobile phases was 1.0 mL/min with UV detection at different wavelengths. The values...
Mandelic acid and its derivatives are important chiral analogs which are widely used in the pharmaceutical synthetic industry. The present study investigated the enantiomeric separation of six mandelic acids (mandelic acid, 2‐chloromandelic acid, 3‐chloromandelic acid, 4‐chloromandelic acid, 4‐bromomandelic acid, 4‐methoxymandelic acid) on the Chiralpak AD‐3 column by supercritical fluid chromatography...
In this study, magnetic multiwalled carbon nanotubes (MMWCNTs) were synthesized and used as adsorbent for preconcentration of chiral pesticide residues (including epoxiconazole, tebuconazole, and metalaxyl) in lettuce, cabbage, and apple. Several parameters affecting the treatment efficiency were investigated, including extraction solvent and absorption solvent. Under the optimal conditions, all three...
In the present paper, we describe several pathways employing immobilized lipase from Candida antarctica B (CAL‐B) as biocatalyst to prepare easily both enantiomers of 3‐(1‐hydroxyethyl)phenol. We have applied hydrolysis with Na2CO3 in organic media under mild conditions. The reaction parameters solvent effect, amount of lipase, and Na2CO3 were examined with 3‐(1‐acetoxyethyl)phenyl acetate as substrate...
Rabeprazole is an effective proton pump inhibitor to treat acid‐related diseases. To achieve the simultaneous determination of rabeprazole enantiomers in human plasma, a chiral LC‐MS/MS method was developed and validated. Acetonitrile including 0.1% ammonium were used as protein precipitating agent. Analytes were separated within 8 minutes on a Chiralpak IC column (4.6 mm × 150 mm, 5 μm). The mobile...
Research on the enantioselective environmental behavior of chiral pesticides has been a hot spot of environmental chemistry recently. In this study, the acute toxicity and digestion of furalaxyl enantiomers were determined on the aquatic algae Scendesmus obliquus. After exposure for 96 hours, the EC50 values for (S)‐furalaxyl and (R)‐furalaxyl were 13.59 and 15.26 mg/L, respectively. In addition,...
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