Recently, strong evidence that supports the presence of an intramolecular C-H···O hydrogen bond in amides derived from the chiral auxiliary α-methylbenzylamine was disclosed. Due to the high importance of this chiral auxiliary in asymmetric synthesis, the inadvertent presence of this C-H···O interaction may lead to new interpretations upon stereochemical models in which this chiral auxiliary is present. Therefore, a series of lactams containing the chiral auxiliary α-methylbenzylamine (from three to eight-membered ring) were theoretically studied at the MP2/cc-pVDZ level of theory with the purpose of studying the origin and nature of the C-Hα···O interaction. NBO analysis revealed that rehybridization at C atom of the C-Hα bond (s-character at C is ~23%) and the subsequent bond polarization are the dominant effect over the orbital interaction energy →σ* (E(2) < 2 kcal/mol), causing an important shortening of the C-Hα bond distance and an increment in the positive charge in the Hα atom.
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http://dx.doi.org/10.3390/molecules22030361 | DOI Listing |
Nat Commun
January 2025
The Institute for Advanced Studies and Hongyi Honor College, Wuhan University, Wuhan, China.
Optically pure 1,2-diols and 1,3-diols are the most privileged structural motifs, widely present in natural products, pharmaceuticals and chiral auxiliaries or ligands. However, their synthesis relies on the use of toxic or expensive metal catalysts or suffer from low regioselectivity. Catalytic asymmetric synthesis of optically pure 1,n-diols from bulk chemicals in a highly stereoselective and atom-economical manner remains a formidable challenge.
View Article and Find Full Text PDFResearch (Wash D C)
December 2024
School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
Chirality has garnered significant attention in the scientific community since its discovery by Louis Pasteur over a century ago. It has been showing a profound impact on chemical, biomedical, and materials sciences. Significant progress has been made in controlling molecular chirality, as evidenced by the several Nobel Prizes in chemistry awarded in this area, particularly for advancements in the asymmetric catalytic synthesis of molecules with central and axial chirality.
View Article and Find Full Text PDFBiopolymers
January 2025
Department of Chemistry, Faculty of Engineering and Science, Bursa Technical University, Bursa, Turkey.
Cellulose is one of the most abundant biopolymers in nature. Despite being the subject of research in various fields, it is not as famous as chitosan in catalyst design. Herein, a novel thiourea-functionalized cellulose (CTU-6) was synthesized as a robust hydrogen bonding catalyst with the degree of substitution (DS) of 0.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
Laboratory of Asymmetric Catalysis and Synthesis, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland.
Chiral cyclopentadienyl (Cp) metal complexes are frequently used in asymmetric catalysis by virtue of their high reactivity and selectivity. Planar-chiral-only rhodium and iridium cyclopentadienyl complexes are particularly promising due to unrestricted chemical space for Cp ligand design while retaining structural simplicity. However, they are currently still niche because of a lack of efficient synthetic strategies that avoid lengthy chiral auxiliary routes or chiral preparatory HPLC resolution of the complexes.
View Article and Find Full Text PDFChem Rev
December 2024
University of Texas at Austin, Department of Chemistry, 105 E 24th St., Welch Hall (A5300), Austin, Texas 78712, United States.
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