홍성우 교수

The development of intermolecular alkene aminopyridylation has great potential for quickly increasing molecular complexity with two valuable groups. Here we report a strategy for the photocatalytic aminopyridylation of alkenes using a variety of N-aminopyridinium salts as both aminating and pyridylating reagents. Using Eosin Y as a photocatalyst, amino and pyridyl groups are simultaneously incorporated into alkenes, affording synthetically useful aminoethyl pyridine derivatives under mild reacti

Abstract Through the formation of an electron donor–acceptor (EDA) complex, strain‐release aminopyridylation of [1.1.1]propellane with N ‐aminopyridinium salts as bifunctional reagents enabled the direct installation of amino and pyridyl groups onto bicyclo[1.1.1]pentane (BCP) frameworks in the absence of an external photocatalyst. The robustness of this method to synthesize 1,3‐aminopyridylated BCPs under mild and metal‐free conditions is highlighted by the late‐stage modification of structural

Abstract Metal‐free, visible‐light‐induced site‐selective heteroarylation of remote C(sp 3 )−H bonds has been accomplished through the design of N‐alkoxyheteroarenium salts serving as both alkoxy radical precursors and heteroaryl sources. The transient alkoxy radical can be generated by the single‐electron reduction of an N‐alkoxypyridinium substrate by a photoexcited quinolinone catalyst. Subsequent radical translocation of the alkoxy radical forms a nucleophilic alkyl radical intermediate, whi

By employing an N-heterocyclic carbene (NHC) catalyst, we developed a versatile catalytic system that enables deaminative cross-coupling reactions of aldehydes with redox-active pyridinium salts. Katritzky pyridinium salts behave as single-electron oxidants capable of generating alkyl radicals enabled by the redox properties of the enolate form of Breslow intermediates. The resultant alkyl radical undergoes efficient recombination with the NHC-bound aldehyde-derived carbonyl carbon radical for t

Phosphatidylinositol 3-kinase α (PI3Kα) is an important regulator of intracellular signaling pathways, controlling remarkably diverse arrays of physiological processes. Because the PI3K pathway is frequently up-regulated in human cancers, the inhibition of PI3Kα can be a promising approach to cancer therapy. In this study, we have designed and synthesized a new series of imidazo[1,2-a]pyridine derivatives as PI3Kα inhibitors through the fragment-growing strategy. By varying groups at the 3- and

Reported herein is a general strategy for the photochemical cross-coupling between <i>N</i>-amidopyridinium salts and various alkyl bromides under photocatalyst-free conditions, granting facile access to various C4-alkylated pyridines. This approach exploits the intriguing photochemical activity of electron donor-acceptor (EDA) complexes between <i>N</i>-amidopyridinium salts and bromide, which provides a photoactive handle capable of generating silyl radicals and driving the alkylation process.

Site-selective C-H functionalization in chemical feedstocks is a challenging and useful reaction in the broad field of chemical research. Here, we report a modular photochemical platform for the site-selective C-H pyridylation of unactivated hydrocarbons via the unique synergistic effects of triplet excited anthraquinone and an amidyl radical-based reverse hydrogen atom transfer (RHAT) agent. The selective pyridylation of tertiary and secondary C(sp³)-H bonds in abundant chemical feed

The radical-mediated C-H functionalization of pyridines has attracted considerable attention as a powerful tool in synthetic chemistry for the direct functionalization of the C-H bonds of the pyridine scaffold. Classically, the synthetic methods for functionalized pyridines often involve radical-mediated Minisci-type reactions under strongly acidic conditions. However, the site-selective functionalization of pyridines in unbiased systems has been a long-standing challenge because the pyridine sc

The selective installation of phosphinoyl and carbamoyl moieties on the pyridine scaffold is an important transformation in synthetic and medicinal chemistry. By employing quinolinone as an efficient organic photocatalyst, we developed a catalytic system driven by visible light that forms phosphinoyl and carbamoyl radicals, which react with various heteroarenium derivatives under mild, transition-metal-free conditions. This straightforward and environmentally friendly synthetic method represents

By utilizing an underexplored reactivity mode of <i>N</i>-aminopyridinium ylides, we developed the visible-light-induced <i>ortho</i>-selective aminopyridylation of alkenes via radical-mediated 1,3-dipolar cycloaddition. The photocatalyzed single-electron oxidation of <i>N</i>-aminopyridinium ylides generates the corresponding radical cations that enable previously inaccessible 1,3-cycloaddition with a broader range of alkene substrates. The resulting cycloaddition adducts rapidly undergo subseq

RMM was negatively associated with development of T2DM in a large sample of young and middle-aged Korean adults. Further research is required to determine whether preservation of muscle mass through intervention affects the risk of T2DM.

Concise and selective: the title one-pot sequence allows formation of the enone functionality and subsequent cross-coupling. The process provides access to highly functionalized cyclic enolones and enaminones from readily accessible β-heteroatom-substituted cyclic ketones.

Pd-catalyzed oxidative Heck reactions of coumarins were developed via simultaneous C-H functionalization at the C3 position of coumarins under aerobic conditions.

A new efficient method for the direct alkenylation of chromones via a palladium(II)-catalyzed C-H functionalization reaction was developed. The use of pivalic acid with Cu(OAc)(3)/Ag(2)CO(3) provided superior reactivity in the cross-coupling of chromones with alkene partners. This approach represents a significant advance over the existing two-step method and afforded various 3-vinylchromone derivatives, which are privileged structures in many biologically active compounds and versatile syntheti

Reported herein is a modular, NiH-catalyzed system capable of proximal-selective hydroamination of unactivated alkenes with diverse amine sources. The key to the successful implementation of this approach is the promotion of NiH insertion into even highly substituted olefins via coordination of the bidentate directing group to the nickel complex. A wide range of primary and secondary amines can be installed in both internal and terminal unactivated alkenes with excellent regiocontrol under the o