이정효 교수

Alkanes are an abundant and inexpensive source of hydrocarbons; thus, development of new methods to convert the hydrocarbon feedstocks to value-added chemicals is of high interest. However, it is challenging to achieve such transformation in a direct and selective manner mainly due to the intrinsic inertness of their C-H bonds. We herein report a tailored Cp*Co(III)(LX)-catalyzed efficient and site-selective intermolecular amidation of unactivated hydrocarbons including light alkanes. Electronic

Herein, we report the development of a tailored cobalt catalyst system of Cp*Co(III)(LX) toward intramolecular C-H nitrene insertion of azidoformates to afford cyclic carbamates. The cobalt complexes were easy to prepare and bench-stable, thus offering a convenient reaction protocol. The catalytic reactivity was significantly improved by the electronic tuning of the bidentate LX ligands, and the observed regioselectivity was rationalized by the conformational analysis and DFT calculations of the

We disclose herein a directing group-assisted nickel-catalyzed intermolecular C(sp3)–H amidation using organic azides as nitrene precursors. With the installation of an electronically tailored directing group, enhanced amidation efficiency was achieved. A series of experimental and computational studies suggested that a putative nickel(III)-nitrenoid species is a key intermediate in the C–N bond-forming process.

This work describes chiral phosphoric acid (CPA)-catalyzed desymmetrizative glycosylation of meso-diol derived from 2-deoxystreptamine. The chirality of CPA dictates the outcome of the glycosylation reactions, and the use of enantiomeric CPAs results in either C4-glycosylated (67 : 33 d.r.) or C6-glycosylated (86 : 14 d.r.) 2-deoxystreptamines. These glycosylated products can be converted to aminoglycosides, and the application of this strategy to the synthesis of protected iso-neamine and iso-k

This article describes studies on the regioselective acetal protection of monosaccharide-based diols using chiral phosphoric acids (CPAs) and their immobilized polymeric variants, (<i>R</i>)-Ad-TRIP-PS and (<i>S</i>)-SPINOL-PS, as the catalysts. These catalyst-controlled regioselective acetalizations were found to proceed with high regioselectivities (up to >25:1 rr) on various d-glucose-, d-galactose-, d-mannose-, and l-fucose-derived 1,2-diols and could be carried out in a regiodivergent fashi

This work describes the development of a new single-pot copper(II)-catalyzed decarboxylative Michael reaction between β-keto acids and enones, followed by in situ aldolization, which results in highly functionalized chiral and achiral cyclohexenones. The achiral version of this Robinson annulation features a hitherto unprecedented Michael reaction of β-keto acids with sterically hindered β,β'-substituted enones and provides access to all carbon quaternary stereocenter-containing cyclohexenones (

We herein disclose the Cp*Co(III)(LX)-catalyzed amidative alkyl migration using 2,6-disubstituted phenyl azidoformates. Upon the cobalt-nitrenoid insertion toward the substituted <i>ortho</i> carbon, an arenium cationic species bearing a quaternary carbon is generated, and a subsequent alkyl migration process is suggested to occur through an unforeseen alkyl-walking mechanism. A quinolinol ligand of the cobalt catalyst system is proposed to facilitate the final product-releasing rearomatization

A regiodivergent oxidative cyclization of ynamide-tethered benzaldehydes has been achieved using an organocatalytic approach based on NHC/base. The method enables the efficient synthesis of aminolactones with high regioselectivity, including the formation of 5- exo products through umpolung β-addition of ynamides. The reaction involves NHC-catalyzed aerobic oxidation of the benzaldehyde moiety followed by cyclization toward the ynamide. Computational and experimental studies have shed light on t

This work provides a comprehensive overview of recent advances in the selective transformation of diols, focusing on diverse organocatalytic strategies and the mechanistic principles underlying selectivity control.

Abstract This Account describes the recent advances in our research program toward the development of cobalt-catalyzed C–H amidation reactions. In particular, synthetic versatilities of obtainable amino products shown to be achieved on the basis of two distinctive mechanistic scaffolds; inner- and outer-sphere pathways. It highlights our approaches to transit the modes of C–N bond formation by introduction of bidentate LX-type ligands into Cp*Co(III) precursors, thereby broadly expanding the sco

We disclose herein a Cp*Co(III)(LX)-catalyzed dearomative Diels-Alder dimerization of 2,6-disubstituted phenyl azidoformates. Upon the postulated cobalt-nitrenoid insertion into the neighboring <i>ortho</i>-carbon, the key intermediate of <i>ortho</i>-quinamine was generated for the subsequent dimeric cycloaddition process. A series of experimental and computational studies suggested that the quinolinol ligand of the cobalt catalyst plays a crucial role in the alcoholic solvent incorporation int

Abstract We herein report an efficient synthetic method for preparing [6‐7‐6]‐icetexane derivatives. This approach employs our previously designed copper‐catalyzed intramolecular cyclization of enyne‐aryl carbonyl substrates to generate a [6‐6‐6]‐tricyclic abietane framework and a subsequent ring expansion protocol for the [6‐7‐6] scaffold. By synergizing these protocols, we established a highly efficient pathway for synthesizing icetexane compounds from readily available enyne‐aryl starting mat

Polyols, such as carbohydrates and other compounds containing multiple hydroxyl groups, represent an important class of molecules. The selective transformations of polyol-containing compounds are of great importance as relatively easily accessible polyol building blocks can be transformed into more synthetic useful compounds. Accomplishing selective transformations of polyols is challenging due to intrinsic complexity of these molecules and unpredictable inherent selectivity of primary and secon

Binding affinity of menthol ligand to the Transient Receptor Potential Melastatin 8 (TRPM8) protein was examined using the computer programs AutoDock Vina and Visual Molecular Dynamics (VMD). A single run with AutoDock Vina predicts 9 possible binding modes of menthol in TRPM8. Among these 9 possible docking products, the mode with the highest affinity between menthol and TRPM8 showed interaction of menthol with residues Tyr754, Asn799, and ASP 802, which have been shown experimentally by others