The catalytic kinetic resolution of cyclic amines with achiral N-heterocyclic carbenes and chiral hydroxamic acids has emerged as a promising method to obtain enantio-enriched amines with high selectivity factors. In this report, we describe the catalytic kinetic resolution of disubstituted piperdines with practical selectivity factors (s, up to 52) in which we uncovered an unexpected and pronounced conformational effect resulting in disparate reactivity and selectivity between the cis- and trans-substituted piperidine isomers. Detailed experimental and computational studies of the kinetic resolution of various disubstituted piperidines revealed a strong preference for the acylation of conformers in which the α-substituent occupies the axial position. This work provides further experimental and computational support for the concerted 7-member transition state model for acyl transfer reagents and expands the scope and functional group tolerance of the secondary amine kinetic resolution.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4601563 | PMC |
| http://dx.doi.org/10.1021/jacs.5b07201 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Metal oxides are promising catalysts for small molecule hydrogen chemistries, mediated by interfacial proton-coupled electron transfer (PCET) processes. Engineering the mechanism of PCET has been shown to control the selectivity of reduced products, providing an additional route for improving reductive catalysis with metal oxides. In this work, we present kinetic resolution of the rate determining proton-transfer step of PCET to a titanium-doped POV, TiVO(OCH) with 9,10-dihydrophenazine by monitoring the loss of the cationic radical intermediate using stopped-flow analysis.
View Article and Find Full Text PDFA C-H Arylation-Based Enantioselective Synthesis of Planar Chiral Cyclophanes.
Angew Chem Int Ed Engl
January 2025
University of Basel, Department of Chemistry, St. Johanns-Ring 19, 4056, Basel, SWITZERLAND.
Despite the growing importance of planar chiral macrocyclophanes owing to their unique properties in different areas of chemistry, methods that are effective in controlling their planar chirality are restricted to certain molecular scaffolds. Herein, we report the first Pd(0)-catalyzed enantioselective intermolecular C-H arylation that induces planar chirality by installing bulky aryl groups through dynamic kinetic resolution (DKR). A computer-assisted approach allowed a fine-tuning of the structure of the employed chiral bifunctional phosphine-carboxylate ligands to achieve high enantioselectivities.
View Article and Find Full Text PDFElectrochemical and physical properties of magnesioferrite nanomaterial and photocatalytic degradation of methylene blue.
Sci Rep
January 2025
UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria, South Africa.
This research successfully synthesized semiconductive magnesioferrite (MgFeO) nanomaterials using a green chemistry method that utilizes the natural extract of Moringa olefeira serving as both a reducing and oxidizing agent. The optical characteristics and crystalline structure of the MgFeO nanomaterials were analysed using photoluminescence, diffuse reflectance spectroscopy, and X-ray diffraction. Additionally, Fourier transform infrared spectroscopy provided valuable insights into the chemical bonding and composition.
View Article and Find Full Text PDFSingle-molecule imaging for investigating the transcriptional control.
Mol Cells
January 2025
Department of Regulatory Science, Graduate School, Kyung Hee University, Seoul 02447, Korea; College of Pharmacy, Kyung Hee University, Seoul 02447, Korea; Institute of Regulatory Innovation through Science (IRIS), Kyung Hee University, Seoul 02447, Korea. Electronic address:
Transcription is an essential biological process involving numerous factors, including transcription factors (TFs) which play a central role in this process by binding to their cognate DNA motifs. Although cells must tightly regulate the kinetics of factor association and dissociation during transcription, factor dynamics during transcription remain poorly characterized, primarily because of the reliance on ensemble experiments that average out molecular heterogeneity. Recent advances in single-molecule fluorescence imaging techniques have enabled the exploration of TF dynamics at unprecedented resolution.
View Article and Find Full Text PDFAbsolute line strength measurements of hydroperoxyl (HO2) radical in the OO-stretching (ν3) fundamental band have been performed by means of mid-infrared time-resolved dual-comb spectroscopy. By employing two sets of dual-comb spectrometers, high-resolution time-resolved spectra of HO2 and HCl, formed in the photolysis reaction system of Cl2/CH3OH/O2, could be, respectively, measured near 1123 and 3059 cm-1. With kinetic simulations, spectral analysis of both HO2 and HCl, as well as the accurate line strength of the HCl R(9) transition at 3059.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!