Language：English   Publisher：Journal of Computational Chemistry  

The regioselective radical C-H trifluoromethylation of aromatic compounds have been shown to proceed in good yield and high regioselectivity when cyclodextrin (CD) is present. Yet, the reaction mechanism and the role of CD during the reaction have remained obscure. To this end, here we performed density functional theory (DFT) calculations to the conformations obtained by semiempirical quantum mechanical molecular dynamics calculations to reveal the reaction mechanism and the role of CD in controlling regioselectivity. The results show that metal salt increases the yield but do not affect the regioselectivity, which we further confirmed by an experiment. In contrast, multiple CD-substrate complex conformations and reaction pathways were obtained, and CD was shown to contribute to improving the regioselectivity by stabilizing the intermediate state via encapsulation. The present study indicates that CDs can increase the regioselectivity by stabilizing the intermediate and product states while only marginally affecting the transition state.

DOI： 10.1002/jcc.27430

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PubMed

Publisher：ACS Catalysis  

We report carbamoylarylation of alkenes using N-aryl oxamic acid derivatives under visible-light irradiation. Reactions of alkenes with carbamoyl radicals generated using N-aryl oxamic acid derivatives to afford Giese-type products or 3,4-dihydroquinolin-2(1H)-ones via ortho-radical addition to an aryl amide moiety have been previously reported. However, this study reveals that the introduction of a removable bulky group onto the nitrogen atom of N-aryl oxamic acids facilitates the radical addition of carbamoyl radicals to alkenes, resulting in 1,4-aryl migration via C(aryl)-N bond cleavage, thus affording arylpropanamides. Various alkenes, such as acrylic acid and styrene derivatives, are successfully applied to the synthesis of a variety of arylpropanamide derivatives, including 1,4-dicarbonyl amides, forming two C-C bonds.

DOI： 10.1021/acscatal.4c00523

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Language：English   Publisher：Organic Letters  

We developed the visible-light-induced hydrodesulfurization of alkyl aryl thioethers via the reductive cleavage of the C(aryl)-S bond using 1-hydroxypyrene as a Brønsted acid-reductant bifunctional photocatalyst. The hydrodesulfurization reaction proceeded under simple reaction conditions (1-hydroxypyrene and Et<inf>3</inf>N in THF under purple LED illumination); this reaction did not require chemicals commonly used for hydrodesulfurization, such as hydrosilanes, transition metal catalysts, and/or stoichiometric amounts of metal reagents. Detailed mechanistic studies based on control experiments, spectroscopic measurements, and computational studies revealed that the cleavage of the C(aryl)-S bond and the formation of the C(aryl)-H bond proceeded via the formation of the ion pair between the radical anion of alkyl aryl thioether and Et<inf>3</inf>N⁺H, resulting in the generation of a sulfur radical. In addition, the 1-hydroxypyrene catalyst was regenerated via hydrogen atom transfer (HAT) from Et<inf>3</inf>N.

DOI： 10.1021/acs.orglett.3c01061

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PubMed

Language：English   Publishing type：Research paper (scientific journal)   Publisher：European Journal of Organic Chemistry  

Novel triarylmethanols and triarylmethyl cations with diphenylamino groups were designed and synthesized. The triarylmethyl cations exhibited near-infrared (NIR) emission in toluene solution, solid film state, and polystyrene (PS) film. The emission intensities of the triarylmethyl cations were strongest in the PS film. The relative quantum yield of the PS film increased as the number of diphenylamino groups increased. In addition, triarylmethanols exhibit dual emission in their aggregated state owing to the intermolecular interactions between triphenyl amine moieties and/or hydroxy groups. These findings are interesting because NIR and dual emissions are not observed in the dimethylamino group-substituted triarylmethyl cation, which is referred to as the “malachite green,” and the corresponding triarylmethanol, respectively.

DOI： 10.1002/ejoc.202200873

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

We have developed the divergent deaminative borylation and hydrodeamination of primary aromatic amines using bis(pinacolato)diboron. These transformations can be switched by the reaction conditions. Mechanistic and computational studies have suggested that the cleavage of the C–N bond and the formation of C–B bond are unlikely to involve free aryl radical intermediates. However, hydrodeamination is shown to proceed via hydrogen atom transfer between the corresponding aryl radical and an ethereal solvent.

DOI： 10.1021/acs.orglett.2c01663

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CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Organic Chemistry  

C-H functionalization has recently received considerable attention because C-H functionalization during the late-stage transformation is a strong and useful tool for the modification of the bioactive compounds and the creation of new active molecules. Although a carbene transfer reaction can directly convert a C-H bond to the desired C-C bond in a stereoselective manner, its application in late-stage material transformation is limited. Here, we observed that the iridium-salen complex 6 exhibited efficient catalysis in asymmetric carbene C-H insertion reactions. Under optimized conditions, benzylic, allylic, and propargylic C-H bonds were converted to desired C-C bonds in an excellent stereoselective manner. Excellent regioselectivity was demonstrated in the reaction using not only simple substrate but also natural products, bearing multiple reaction sites. Moreover, based on the mechanistic studies, the iridium-catalyzed unique C-H insertion reaction involved rate-determining asynchronous concerted processes.

DOI： 10.1021/acs.joc.2c00470

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PubMed

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1002/ejic.202100776

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1021/acs.orglett.1c01831

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1021/acscatal.1c01813

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1021/acs.jnatprod.9b00947

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1021/acscatal.0c00370

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.tet.2019.130646

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1039/c9dt01887e

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1002/chem.201900733

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1002/jcc.25550