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In this paper, we have studied the chiroptical properties of a family of o‐oligo(phenyleneethynylene) (o‐OPE) derivatives with different steric hindrance. Experimental results show high dissymmetry factors (gabs and glum up to 1.1 × 10−2) and very similar electronic circular dichroism (ECD) and circularly polarized luminescence (CPL) for all the derivatives that make this basic o‐OPE scaffold a robust...
Three β‐keto sulfoxides (1–3) were synthesized in enantiopure form and investigated by means of circular dichroism (CD) spectroscopy, both in electronic and vibrational range (ECD, VCD), in combination with quantum chemical calculations. For compound 2, the X‐ray structure was available; thus, the ECD in the solid state was also considered to reveal the differences between the molecular species in...
The application of several immobilized lipases has been explored in the enantioselective esterification of (R,S)‐2‐methylbutyric acid, an insect pheromone precursor. With the use of Candida antarctica B, using hexane as solvent, (R)‐pentyl 2‐methylbutyrate was prepared in 2 h with c 40%, eep 90%, and E = 35, while Thermomyces lanuginosus leads to c 18%, eep 91%, and E = 26. The (S)‐enantiomer was...
Vibrational and electronic circular dichroism (VCD and ECD) spectra of 3 optically active bilirubin analogs with propionic acid groups replaced by (1) 1‐(S)‐methylpropyl groups, (2) 3‐acetoxy‐1‐(S)‐methylpropyl groups, and (3) 1‐(S)‐2‐(R)‐dimethyl‐2‐(methoxycarbonyl)ethyl groups have been recorded at different concentrations in chloroform. The aliphatic chains attached to C‐8 and C‐12 of the 3 chosen...
The cover image, by Simone Ghidinelli et al., is based on the Special Issue Article On the aggregation of bilirubinoids in solution as evidenced by VCD and ECD spectroscopy and DFT calculations, DOI: 10.1002/chir.22776.
Enantioseparation of the antidiarrheal drug, racecadotril, was investigated by liquid chromatography using polysaccharide‐type chiral stationary phases in polar organic mode. The enantiodiscrimininating properties of 4 different chiral columns (Chiralpak AD, Chiralcel OD, Chiralpak AS, Chiralcel OJ) with 5 different solvents (methanol, ethanol, 1‐propanol, 2‐propanol, and acetonitrile) at 5 different...
A profoundly time‐efficient chemoenzymatic method for the synthesis of (S)‐3‐(4‐chlorophenoxy)propan‐1,2‐diol and (S)‐1‐chloro‐3‐(2,5‐dichlorophenoxy)propan‐2‐ol, two important pharmaceutical intermediates, was successfully developed using Pseudomonas fluorescens lipase (PFL). Kinetic resolution was successfully achieved using vinyl acetate as acylating agent, toluene/hexane as solvent, and reaction...
The use of stereodynamic probes is becoming one of the leading strategies for the fast and effective determination of enantiomeric excess. Recently, we reported a series of novel molecular architectures based on a modified tris(2‐pyridylmethyl)amine complex (TPMA), which are able to amplify the electronic CD, in the case of Zn(II) assemblies and vibrational CD, in the case of Co(II) assemblies. Herein,...
The relative merits of the methods employed to determine enantiomeric excess (ee) values and absolute configurations of chiral arene and alkene cis‐1,2‐diol metabolites, including boronate formation, using racemic or enantiopure (+) and (−)‐2‐(1‐methoxyethyl)phenylboronic acid (MEPBA), are discussed. Further applications of: 1) MEPBA derived boronates of chiral mono‐ and poly‐cyclic arene cis‐dihydrodiol,...
The transition dipole coupling model allows to vary systematically many parameters, such as chromophore geometries and transition dipoles. We used it to explore conditions favorable to chirality enhancement observed in many experiments on protein amyloidal precipitates. Stacking of β‐sheet planes has been identified as a particularly powerful mechanism of the enhancement.
We recently reported a new C3‐symmetric (R)‐phenylglycinol N‐1,3,5‐benzenetricarboxylic acid‐derived chiral high‐performance liquid chromatography (HPLC) stationary phase (CSP 1) that demonstrated better results as compared to a previously described N‐3,5‐dintrobenzoyl (DNB) (R)‐phenylglycinol‐derived CSP. Over a decade ago, (S)‐leucinol, (R)‐phenylglycine, and (S)‐leucine derivatives were used as...
The application of ionic liquids as solvents for transesterification of prochiral pirymidine acyclonucleoside using lipase (EC 3.1.1.3) Amano PS from Burkholderia cepacia (BCL) is reported. The effect of using medium reaction, acyl group donor, and temperature on the activity and enantioselectivity of BCL was studied. From the investigated ionic solvents, the hydrophobic ionic liquid [BMIM]PF6] was...
In our effort towards measuring the parity violation energy difference between two enantiomers, a simple chiral oxorhenium complex 5 bearing enantiopure 2‐mercaptocyclohexan‐1‐ol has been prepared as a potential candidate species. Vibrational circular dichroism revealed a chiral environment surrounding the rhenium atom, even though the rhenium is not a stereogenic center itself, and enabled to assign...
Readily available chiral trianglimine and their (poly)oxygenated congeners represent a unique class of macrocyclic rigid compounds optimal for testing electronic and vibrational circular dichroism exciton chirality methods. Electronic and vibrational circular dichroism spectra of such trianglimines are strongly affected by polar substituents in macrocycle skeletons. Double substitution by OH groups...
The first successful enantioseparation of representative O,O‐diphenyl‐N‐arylthioureidoalkylphosphonates, (±)‐Ptc‐ValP(OPh)2 & (±)‐Ptc‐LeuP(OPh)2 and thiourylenedi(isobutyl phosphonate), Tcm[ValP(OPh)2]2 on analytical and semipreparative scale was achieved by high‐performance liquid chromatography using polysaccharide‐based chiral stationary phases (CPs). Atc‐AAP(OPh)2 was obtained using modified...
Racemic natural products are rarely produced in plants and microorganisms and are thought to be the result of nonenzymatic, spontaneous reactions. These compounds are often highly complex with multiple contiguous chiral centers that present a challenge to organic synthesis. Formation of these racemates often occurs by cyclization reactions that can generate multiple stereocenters from achiral precursors...
The present study describes a generic strategy using capillary electrophoretic (CE) method for chiral enantioseparation of anti‐Alzheimer drugs, namely, donepezil (DON), rivastigmine (RIV), and antifungal drugs, namely, ketoconazole (KET), Itraconazole (ITR), fluconazole (FLU), and sertaconazole (SRT) in which these drugs have different basic and acidic properties. Several modified cyclodextrins (CDs)...
Piperonyl ring is found in a number of naturally occurring compounds and possesses enormous biological activities. There are many studies in the literature with compounds containing a piperonyl ring, but there are very few studies on the synthesis of chiral piperonyl carbinol. The objective of this study was to determine the microbial reduction ability of bacterial strains and to reveal the effects...
The absolute stereochemistry of chiral carboxylic acids is determined as a di(1‐naphthyl)methanol ester derivative. Computational scoring of conformations favoring either P or M helicity of the naphthyl groups, capable of exciton‐coupled circular dichroic coupling, leads to a predicted stereochemistry for the derivatized carboxylic acids.
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